IL17A and breast cancer: This is followed by the recruitment of myeloid-derived suppressor cells (MDSC) into the tumor niche—these cells secrete TGF-β and interleukin-6 (IL-6), which results in the differentiation of CD4+ T cells into Th17 cells that secrete IL-17, a mechanism further increasing CXCL1 expression in breast cancer cells [59,60,61].