PCNA and neoplasm: Given the variation of IGF1R/PCNA colocalization within single tumor subtypes and the putative response to radio- and chemotherapy, we conducted extended studies of two tumor subtypes that had among the strongest IGF1R/PCNA colocalization signals in the clinical cancer panel–invasive oropharyngeal SCC (OPSCC) and high-grade ovarian cancer (HGSC).