SLC3A1 and cystinuria: We wondered whether the sex-dependent expression of Slc7a13 was the cause of the sex differences of Slc3a1 KO induced cystinuria, thus we generated Slc7a13 KO mice with CRISPR/Cas9 technology (Fig. S2) and crossed them with Slc3a1 KO mice to make a double KO (DKO) mouse (Fig. 2C).