PGP and colorectal carcinoma: Furthermore, Yuan et al12 discovered that cinobufagin, a material derived from the Asiatic toad’s posterior auricular glands and skin, influenced the intonation of P-gp activity in human P-gp-overexpressing colorectal carcinoma cells, involving Caco-2/ADR, HCT116/L, and LoVo/ADR, implying that it might be used in combination with chemotherapeutics.