As data on the potential heterogeneity of MTAP expression in muscle-invasive urothelial carcinomas are lacking, we analyzed all available tumor containing tissue blocks from 41 consecutive primary pT2-4 cancers, and also utilized a “urothelial bladder cancer heterogeneity tissue microarray (TMA) containing five different samples from five different tumor blocks of 105 further pT2-4 cancers. The gene discussed is MTAP; the disease is bladder transitional cell carcinoma.