PGP and colorectal cancer: In this regard, bufalin, another active bufadienolide compound with very similar structure to arenobufagin and gamabufotalin, has been reported to efficiently reverse P-gp-mediated multidrug resistance (MDR) through not only inhibiting the efflux function of P-gp but also downregulating its protein expression in human colorectal cancer cells and it’s xenografts [45].