The function of NPC1L1 (NPC1 like intracellular cholesterol transporter 1, ENSG00000015520) is as follows. Plays a major role in cholesterol homeostasis (PubMed:22095670). Critical for the uptake of cholesterol across the plasma membrane of the intestinal enterocyte (PubMed:22095670). Involved in plant sterol absorption, it transports sitosterol, although at lower rates than cholesterol (By similarity). Is the direct molecular target of ezetimibe, a drug that inhibits cholesterol absorption and is approved for the treatment of hypercholesterolemia (PubMed:15928087). May have a function in the transport of multiple lipids and their homeostasis, thereby influencing lipid metabolism regulation (PubMed:15671032). May be involved in caveolin trafficking from the plasma membrane (By similarity). In addition, acts as a negative regulator of NPC2 and down-regulates its expression and secretion by inhibiting its maturation and accelerating its degradation (PubMed:22095670). {ECO:0000250|UniProtKB:Q6T3U3, ECO:0000250|UniProtKB:Q6T3U4, ECO:0000269|PubMed:15928087, ECO:0000269|PubMed:22095670, ECO:0000305|PubMed:15671032}.