MUC4 and breast neoplasm: Among these 80 genes, the genes with top mutation rates in human PPAPA/TP53I breast tumors include KMT2C (11%), KMT2D (6%), NOTCH1 (2.9%), COL22A1 (2.9%), MUC4 (2.5%), and PTPRM (2.1%), most of which are known breast cancer related genes 22, 23.