Characterization of basal cell markers in normal prostate samples, canine p63+ PC and canine p63- PC.

<p>(A) p63 immunohistochemical expression in a normal prostate gland. Positive basal cells were observed in a discontinuous basal cell layer. (B) p63+ tumor showing diffuse nuclear p63 expression by neoplastic cells. (C) p63- tumor presenting no p63 expression (blue staining). Few non-neoplastic basal cells with nuclear p63 expression (internal control–black arrows) were observed. (D) Immunohistochemical staining of high molecular weight cytokeratin (HMWC) in a normal prostate gland. Positive staining was observed in few basal cells (brown staining—white arrows) establishing a discontinuous basal cell layer. (E and F) Diffuse HMWC expression in p63+ and p63- tumors, respectively. (G) CK5 immunohistochemical expression in canine normal samples. There was a discontinuous basal cell layer with few CK5 positive cells (brown staining). (H) p63+ tumor showing diffuse CK5 expression (brown staining) in all neoplastic cells. (I) p63 tumor showing no CK5 expression by neoplastic cells (blue staining). An atrophic prostatic gland (black arrow) was observed presenting diffuse CK5 expression (internal control). (J) CK8/18 expression in normal prostate. Positive cytoplasmic expression was observed in the epithelial luminal cells (brown staining). p63+ (K) and p63 (L) tumors presented diffuse cytoplasmic staining in all neoplastic cells (brown staining). The negative staining can be observed as a blue signal.