Both cases showed deep deletions of CDKN1B by sequencing, however the tumor on the left demonstrates homogeneous loss of p27 protein, suggestive of a clonal alteration, while the tumor on the right shows heterogeneous loss of p27 in some (arrow) but not all (arrowhead) tumor cells, suggestive of a subclonal alteration in CDKN1B. In both cases, benign glands (B) provide an internal positive control for p27 staining. All images reduced from 200x magnification.