TSC1 and Renal cyst: Fnip1Tsc1 double-null mice developed large cystic kidneys (kidney/brain ratio mean 1.79) by 4 weeks of age (Fig 8A and 8B) whereas Tsc1 null mice had normal appearing kidneys at 4 weeks (Figs 8A and 7C), and did not develop cystic kidneys of comparable kidney/brain weight ratio as Tsc1Fnip1 double null mice until ~10 weeks of age.