PTPRD and cancer: For example, in the cumulative data for nine cancer types, the protein receptor tyrosine phosphatase PTPRD has many more mutated sites than PTPRS, while PTPRF is rarely mutated; in seven cancers, the Discs large homologue DLG2 is by far the most often mutated, DLG1 second, and DLG3 and DLG4 rarely mutated; the EGF receptor family member ERBB4 carries far more mutations than EGFR, while ERBB2 (HER2) and ERBB3 have relatively few nucleotides mutated in seven cancers (table 1; electronic supplementary material, table S3).