Thus, while published data support a higher level of GM-CSF expression in basal breast cancer samples [50], further studies are needed to identify the specific signaling pathways regulating GM-CSF expression in TNBC cells, and to determine whether exogenous factors such as serum, hormones, or growth factors induce or enhance production of GM-CSF in all subtypes of breast cancer cells. Here, CSF2 is linked to breast cancer.