PIK3CA and breast cancer: To examine the mechanism of FSCN1 in cancer cells under IR treatment, we performed colony formation assays in a panel of cancer cell lines, including HeLa (a cervical adenocarcinoma-derived PIK3CA-WT cell line), CaSki cells (a cervical squamous cell carcinoma cell line that is heterozygous for PIK3CA-E545K) (Figure 2C), MDA-MB-231 (a breast cancer PIK3CA-WT cell line) and T47D (a breast cancer cell line that harbors the H1047R mutation with amplified PIK3CA) (Figure 2D).