CYP3A4 and colon carcinoma: Many drug interactions have been shown to involve both p-glycoprotein and CYP3A4 due to overlapping substrate specificity between them, and similarities in their inhibitors and inducers, as for example, with the coinduction of CYP3A4 and p-glycoprotein by rifampin in human LS180 colon carcinoma cells [86].