POLR2A and cancer: POLR2A encodes the largest subunit of RNA polymerase II complex in eukaryotes and drives the transcription of mRNAs.[40, 41, 42] Inhibition of POLR2A induces cell senescence,[43] and reduces the tumor growth in triple negative breast cancer,[41] colorectal cancer,[42] and gastric cancer,[44] suggesting that POLR2A is essential for the survival of cancer cells.