FLCN forms a complex with folliculin-interacting proteins 1 and 2 (FNIP1 and FNIP2) (Figure 4), and kidney-specific double homozygous inactivation of FNIP1/2 or FLCN in mice results in enlarged multi-cystic kidneys [135, 137–139]. This evidence concerns the gene FLCN and Renal cyst.