ABCB1 and neoplasm: However, when G-Rg3 was coadministered with verapamil, a P-glycoprotein inhibitor, the G-Rg3 efflux in Caco-2 cells was lowered, the small intestinal absorption rate of G-Rg3 in the rat models was increased, the concentration levels of G-Rg3 were elevated in the intestine and plasma, and its tumor-preventive abilities in the tumorigenesis rat model induced by B(a)P were also augmented.