ERBB2 and breast cancer: To determine whether ITGA6 expression is associated with radiation sensitivity in breast cancer, we measured the expression of ITGA6 in six breast cancer cell lines, including MCF7 (HR+/HER2−), BT474 (HR+/HER2+), SKBR-3 (HR−/HER2+) and MDA-MB-231, BT549 and HCC1937 (HR−/HER2−) and determined their sensitivities to the radiotherapy.