PENK immunohistochemistry of prostate and bladder. (a) In prostate, the PENK antibody stains the stroma in a pattern that is similar to that by CD56 . The smooth muscle wall of a large blood vessel is also stained (black arrow, left panel). Benign glands appear to be stained at the luminal surface, but this staining is likely non-specific because it was present in the control without the primary antibody (in which the stromal staining was not seen). (b) In bladder, both the urothelium (blue arrow) and stroma (red arrow) of the lamina propria are not stained. Stained are the muscle bundles of the muscularis propria.
Goo et al. BMC Urology 2005 5:17 doi:10.1186/1471-2490-5-17