IL4 and breast cancer: Interestingly, breast cancer cells co-cultured with IL-4-activated macrophages exhibited a profound increase in cellular miR-223 levels (2.7 ± 0.5- and 3.3 ± 0.98-fold in SKBR3 and MDA-MB-231 cells, respectively) relative to cells that were not co-cultured (blank) or were co-cultured with unactivated macrophages (Figure 1C).