CXCL1 and breast cancer: CXCL1 increases the proliferation of breast cancer cells, as has been shown in experiments on triple-negative MDA-MB-231 breast cancer lines, triple-negative HCC-1937 breast cancer cells, HER2-negative MCF-7 cells, and HER2-positive SKBR3 breast cancer cells (ER−PR−HER2+) [78].