PNPLA2 and vitamin A deficiency: In addition to the observation of this study that KIAA1363 affects RE turnover of HSCs, previous reports on ATGL-deficient and HSL-deficient mice have shown that any of these enzymes plays a critical role in vitamin A homeostasis as none of these mouse models develop signs of vitamin A deficiency (e.g., reduced plasma ROH levels or changes in hepatic RE levels, respectively) (6, 14, 15).