ABCB4 and cholestasis: Previously, the genetic overexpression technique of intact or mutant transporters such as ABCB4, ABCB11, ATP8b1, in human embryonic kidney (HEK293T) cells, intestinal cancer cell lines (Caco-2 cells), or Madin–Darby canine kidney II (MDCKII) cells has been used to study progressive cholestasis with genetic mutations.[26], [27], [28], [29], [30], [31] However, such an approach has limitations in recapitulating the physiological transport machinery of human hepatocytes, making them less optimal for studies of liver pathophysiology and drug screening.32