ERBB2 and breast cancer: Interestingly, immunofluorescence (IF) staining and PM extraction assays showed that HER2+ breast cancer cell lines SK-BR-3 and BT-474 displayed clear PM localization of DPAGT1; however, it was rarely detected at the PM of cell lines that are not HER2+, such as MDA-MB-231 or MCF-7 (Figure 4, A and B).