While in human breast cancer (MCF-7) and cervical carcinoma (HeLa) cells, the decline in DNMT1 expression and enhancement of apoptosis by shikonin were correlated with the enhancement of caspase-3, PARP cleavage and p73 expression, and decreased BCL-2 expression with activation of the p16INK4A tumor suppressor gene [172]. Here, CDKN2A is linked to breast cancer.