ARAP1 and breast cancer: Meanwhile, ARAP1-AS1 exhibited a higher expression in several BC cell lines (MDA-MB-468, SKBR3, MCF7 and MDA-MB-231) than that in the normal human mammary epithelial cell MCF-10A, and the highest level of ARAP1-AS1 was examined in MCF7 and MDA-MB-231 cells (Figure 1B) that were chosen for loss-of-function assays.