CPT1A and nonpapillary renal cell carcinoma: Interestingly, a report describing a genetic screen for shRNAs that could increase survival of renal proximal epithelial cells (the proposed cell of origin for ccRCC) after treatment with severe hypoxia (0.2% O2 for 48 h) identified both FBP1 and CPT1A as candidate genes whose suppression led to survival32.