SLC22A4 and cystinuria: As L-Erg is transported by OCTN1 (Slc22a4) and as Slc22a4−/− mice lack L-Erg in the kidneys [14], we crossed the Slc22a4−/− mice with our cystinuria mice model (Slc7a9−/−) looking for differences in the rate of lithiasic mice related to OCTN1 loss (shown in Figure 6 and Table 1).