Resistance to DOX was significantly enhanced in fibroblasts derived from KO mice with targeted Trp53 gene, MCF-7/Adr breast cancer cells with some deletion within exon 5 of the Trp53 gene, KATOIII stomach cell line, and RCM-3 rectum cell line with some deletions in the Trp53 gene [6, 11, 12]. This evidence concerns the gene TP53 and breast carcinoma.