We evaluated this for 13 genes, with a variety of cancer functions: 5 oncogenes (BRAF, EGFR, ERBB2, KRAS, PIK3CA) where “oncogene addiction” has been observed, 5 genes (PARP1, RAD52, POLQ, USP1, PRMT5) with known synthetic lethal relationships, and 3 genes (PTPN11, MDM4, CYFIP1) labeled as having “differential dependencies” in a study of gene dependencies in DepMap (Tsherniak et al. 2017); additional detail in Section 2. This evidence concerns the gene PIK3CA and cancer.