IL7R and lymphopenia: A role of ATP11C in maintaining biophysical properties (e.g. lipid asymmetry) of cell membranes is supported by the observation that Atp11c knock-out mice suffer from lymphopenia [37], which may be due to a defect in the transition from the pro- to the pre-B cell stage of B-cells, a process requiring clathrin-mediated endocytosis of ligand-bound interleukin-7 receptor.