These two mutation signatures are frequently coincident in human tumors but can occur separately as reported for over 20 B cell lymphoma cell lines, urothelial carcinomas with micropapillary histology, ApcMin colorectal tumors in A3A transgenic mice, and yeast and human cells defective in uracil DNA glycosylase or the translesion DNA polymerase Rev1.11 This evidence concerns the gene UNG and urothelial carcinoma.