PTPRR and neoplasm: We previously reported a similar association between pSTAT3 (Y705) expression and mutation of a group of putative PTPR tumor suppressor genes, including PTPRD. [4] When each gene is considered individually rather than as a group, PTPRD is the only PTPR family member for which mutation is significantly associated with pSTAT3 (Y705) expression (S4 Fig).