lines are also based on these cells. Native proteins of interest Depending on various conditions, the gene expression of HEK 293 cells may vary. The following proteins of interest (among many others) are commonly found in untreated HEK 293 cells: Corticotrophin releasing factor type 1 receptor Sphingosine-1-phosphate receptors EDG1, EDG3 and EDG5 Muscarinic acetylcholine receptor M3 Transient receptor potential TRPC1, TRPC3, TRPC4, TRPC6 Bioethics Alvin Wong argues that despite the uncertainty over the origin of the fetus used to obtain the cell line, circumstantial evidence strongly suggests that it came from a voluntary abortion. To some Catholics and Eastern Orthodox Christians, this presents an ethical dilemma for using HEK 293 and derivative products, such as vaccines and many medications. On 21 December 2020, the Roman Catholic Congregation for the Doctrine of the Faith, with the approval of the Pope, stated that “it is morally acceptable to receive COVID-19 vaccines that have used cell lines from aborted fetuses in their research and production process”, but only where other alternatives are non-existent (or currently unavailable), or when there is the risk of a worse danger. During the COVID-19 pandemic, anti-vaccination activists noted that HEK 293 cells are used in the manufacturing of the Oxford–AstraZeneca COVID-19 vaccine (AKA AZD1222). The cells are filtered out of the final products. According to pharmaceutical companies, such as Regeneron Pharmaceuticals, the modern cell line is so far removed from its origin that it is no longer considered fetal tissue. See also Immortalised cell line References External links HEK 293 Transfection and Selection Data @ Cell-culture Database A HEK293 Cell Database 293 Cells (CRL-1573) in the ATCC database Transcript of FDA meeting, in which, starting page 77, van der Eb describes in detail the origin of HEK 293 cell 293T in the Culture Collections of Public Health England Cellosaurus entry for HEK 293 and HEK 293T ATCC entry for 293T Human cell lines Bioethics