CDKN1A and in situ carcinoma: Other studies carried out in breast cancer (MCF7) and colon cancer (LS174T) cell lines induced to senescence by chemotherapy (CIS) showed that p21 can regulate the expression of CD47 and that its union with TSP1 works in order to maintain the senescent state; these kinds of cells escaped senescence by decreasing p21 and CD47 [51].