However, as observed in the LTL313B/H model, there exists intra-tumoral heterogeneity within primary PCa such that molecular analyses resulting from a single biopsy site may not detect all CBX2-overexpressing foci. Therefore, we propose that positive CBX2 IHC staining in at least one core biopsy could be incorporated as an unfavorable prognostic marker that could be interpreted in the context of currently used methods such as TNM staging and Gleason score. The gene discussed is CBX2; the disease is posterior cortical atrophy.