This is consistent with the evidence of the inverse relationship between apoptosis and p21cip1 levels, and the molecular mechanism underlying this notion was finally elucidated by Zhang et al., who demonstrated how, in response to high levels of doxorubicin, p53 inhibits p21cip1 expression through DNMT3a in colorectal cancer cells [47]. Here, TP53 is linked to colorectal cancer.