PTEN and colonic neoplasm: In this study, we take advantage of a classic genetic modifier screen approach to identify bona fide regulators of a 4-hit model targeting Drosophila orthologs of KRAS, TP53, PTEN, and APC, 4 genes recurrently mutated in colon tumors, as well as KRAS alone, which represents one of the most commonly observed pathway alterations in human tumors (Cancer Genome Atlas Network 2012).