ABCB4 and gallbladder disease 1: The phenotyping study of bile and cholesterol crystallization in ABCB4 KO mice could be helpful in establishing a standard for the diagnosis of LPAC in patients because needle-like “anhydrous” cholesterol crystals, aggregated solid cholesterol crystals as bound by mucin gel, or cholesterol microlithiasis can be found by phase contrast and polarizing light microscopy in endoscopically collected hepatic or duodenal bile.