Expression of HIP1 in normal human tissues. (a) Endothelium of a cortical blood vessel shown in transverse section. (b) Breast ductal epithelia displayed moderate HIP1 staining. (c) Stomach epithelial cells displayed moderate HIP1 staining. (d) HIP1 was highly expressed in the distal renal tubules, seen here interspersed with weakly stained proximal renal tubules. (e and f) Colonic columnar epithelium lacked HIP1 staining (e), as did normal prostatic epithelium (f). The high staining of the stroma of the colon (e) is mostly endothelia of the blood vessels. Magnification, ×400. Scale bar, 50 μm. There was no staining when secondary antibody was used alone as a negative control.