CDKN2A and ductal breast carcinoma in situ: Furthermore, we noted that alterations in TP53, RB1, TP53I3 and CDKN2A, known to be associated with apoptotic responses and cell cycle arrest, were highly enriched in stem-like cells of tumors, were highly enriched in stem-like cells of tumors, such as in cases of ATC, DCIS and PDAC (Fig. 2G, Table S2).