Considering all of the above, the present study aimed to investigate, on the one hand, the impact of P4503A4 and UGT1A10 overexpression in breast MCF-7 and colon HCT116 cancer cells on C-1305 and C-1311 metabolism, and, on the other hand, their potency of modulating such enzyme activity following drug’s treatment. This evidence concerns the gene UGT1A10 and cancer.