TP53 and cancer: The TPC and TPAC tumors displayed a ductal-like phenotype and, accordingly, strongly expressed the ductal cancer cell marker cytokeratin 19 (CK-19) (Supplemental Figure 4A), yet the TPAC genotype with loss of RelA/p65 and p53 had an even more ductal-like appearance (Supplemental Figure 4, A and C), more desmoplasia (Supplemental Figure 4C), and a lower cancer cell proliferation rate (Supplemental Figure 4B) than the TPC mice.