PKIB and chromophobe renal cell carcinoma: PKIB mRNA is overexpressed in 13 out of 31 cancer types, including bladder urothelial carcinoma, breast invasive carcinoma, glioblastoma multiforme, kidney chromophobe, prostate adenocarcinoma, etc. However, it is downregulated in two different tumors, acute myeloid leukemia and stomach adenocarcinoma (Fig. 1A), indicating that PKIB might perform different biological functions depending on the tumor background.