TP53 and colorectal cancer: POLR2A is in close proximity to TP53 (encoding the tumor suppressor p53) on chromosome 17, and genomic deletions that remove TP53 in colorectal tumors frequently remove neighbouring genes, including POLR2A. Hemizygous loss of both TP53 and POLR2A was observed in some colorectal cancer (CRC) cell lines, which correlated with a reduced expression of RPB1 and a markedly increased sensitivity to α-AMA in vitro.