The Kir2.1 inward-rectifier potassium ion channel is a lipid-gated ion channel encoded by the KCNJ2 gene. A defect in this gene is associated with Andersen-Tawil syndrome. A mutation in the KCNJ2 gene has been shown to cause short QT syndrome. In neurogenetics, Kir2.1 is used in Drosophila research to inhibit neurons, as overexpression of this channel will hyperpolarize cells. In optogenetics, a trafficking sequence from Kir2.1 has been added to halorhodopsin to improve its membrane localization. The resulting protein eNpHR3.0 is used in optogenetic research to inhibit neurons with light. Expression of Kir2.1 gene in human HEK293 cells induce a transient outward current, creating a steady membrane potential close to the reversal potential of potassium. Kir2.1 has been shown to interact with: DLG4, Interleukin 16, TRAK2 GeneReviews/NCBI/NIH/UW entry on Andersen-Tawil syndrome OMIM entries on Anderson-Tawil syndrome KCNJ2+protein,+human at the US National Library of Medicine Medical Subject Headings Kir2.1+channel at the US National Library of Medicine Medical Subject Headings

The 2020 presidential campaign of Beto O'Rourke, the U. S. Representative for Texas's 16th congressional district from 2013 to 2019, was announced on March 14, 2019. Beto O'Rourke had attracted national attention for his unsuccessful campaign against Ted Cruz in the 2018 Senate election in Texas. O'Rourke suspended his campaign on November 1, 2019. On March 2, 2020, O’Rourke endorsed Joe Biden after Amy Klobuchar, Pete Buttigieg endorsed him. O'Rourke gained prominence on the national stage for challenging incumbent Republican Senator Ted Cruz in the 2018 Senate election in Texas, he lost by a margin of less than three percent. His Senate campaign earned him a reputation as an effective fundraiser, his $80 million haul is the highest amount of money raised by a Senate candidate to date. In late 2018, speculation began that O'Rourke might run in the 2020 United States presidential election. Before the midterm elections, The New Republic claimed that O'Rourke's Senate campaign was laying the groundwork for a potential presidential bid since he was to lose his Senate race.

However, O'Rourke had ruled out a presidential bid when asked on the campaign trail. He told MSNBC, "I will not be a candidate for president in 2020. That’s, I think, as definitive as those sentences get."After losing the Senate race in Texas, O'Rourke mentioned at a town hall meeting that he and his wife had made a decision not to rule anything out. Meanwhile, CNBC reported that O'Rourke's senatorial campaign team had held discussions with senior operatives who worked on former President Barack Obama's campaign as O'Rourke considered a run for the presidency. On March 14, 2019, O’Rourke announced that he is running for president for the 2020 election; the first outlet confirming his announcement was KTSM-TV, El Paso's local NBC-affiliated TV station, where his former brother-in-law was once the news director. On April 12, O'Rourke held a rally in the gym of H. E. McCracken Middle School in Bluffton, South Carolina where he stated that the United States could have border security through "treating people with respect and dignity" rather than through President Trump's US-Mexico border wall, accused Trump of trying to divide America.

On April 27, O'Rourke held a rally at Los Angeles Trade-Technical College where he delivered condolences for the Poway synagogue shooting that occurred hours earlier and pledged that they would support their words with actions to ensure that "in this country that sees more than 30,000 gun deaths every year, a rate not seen anywhere else in the world, that we will insist on universal background checks for everyone, without loopholes or exceptions."On April 28, O'Rourke held a town hall at the United Irish Cultural Center in San Francisco, California where he reflected on the two weeks that San Franciscans spent "wearing masks on their face last year because of the smoke that came here from wildfires that raged at historic levels" and said that he would block the Keystone XL Tar Sands pipeline as president. On May 21, O'Rourke participated in a CNN town hall moderated by Dana Bash. According to Nielsen Media Research, the town hall attracted 714,000 viewers and CNN saw a 29 percent decrease in total viewers when compared to the Tuesday night average of CNN throughout 2019.

On June 1, O'Rourke delivered remarks at the California Democratic Party Convention in San Francisco, referring to California and his home state of Texas as "two border states" that would share with the rest of the United States "that our security will not be purchased through walls or putting kids in cages."On June 6, O'Rourke spoke at the Democratic National Committee's I Will Vote Gala fundraiser in Atlanta, reiterating his support for abortion rights and announcing a proposal meant to register 50 million new voters in addition to preventing Secretary of State offices from purging voter rolls. He supported making Election Day a national holiday. On June 15, O'Rourke participated in a South Carolina forum, expressing his intent to push for more affordable housing options and that his administration would "complement extraordinary local leadership with federal resources and funding."On June 27, while touring a migrant children detention facility in Homestead, Florida, O'Rourke called the detention centers the byproduct of Trump's rhetoric on immigration and said that everyone needed "to stand up and reclaim this country and what we mean to ourselves, to the rest of the world and to these kids", citing Trump as responsible for the detention facilities but everyone else as responsible for, in the White House "going forward."On July 7, O'Rourke held a campaign rally at Marathon Music Works in Nashville, where he pledged to grant citizenship to recipients of the Deferred Action for Childhood Arrivals program and to release asylum seekers from federal detention facilities.

On July 11, O'Rourke delivered remarks at the national convention of the League of United Latin American Citizens in Milwaukee, saying that the United States did not "need to round up people" to keep its citizens safe and stated that he would "lead the effort of rewriting the immigration laws in our own image" if he was elected president. On July 24, O'Rourke held a presidential forum in Detroit, Michigan and a town hall that day in Flint, where he called climate change the "greatest existential challenge" facing both the United States and the planet. Speaking after the 2019 El Paso shooting, during an August 5 interview with Chris Cuomo of CNN, O'Rourke called Trump the "most racist Preside