Parvalbumin is a cytosolic calcium-binding protein expressed in the distal convoluted tubule of the renal nephron that is structurally and functionally similar to calmodulin and troponin C. Among epithelial renal tumors, the reactivity for parvalbumin is observed in chromophobe renal cell carcinomas and frequently in oncocytomas. This protein is thought to be involved in muscle relaxation.