CCL2 and breast cancer: Another illustration to a situation in which Notch receptor-expressing BC cells and macrophages cross-talk with one another, was found in a recent study demonstrating that TAM-derived transforming growth factor β1 (TGFβ1) has activated the Notch1 pathway in basal-like BC cells, giving rise to increased production of IL-1β and of the monocyte chemoattractant CCL2 in the presence of macrophages [90]; as a result, the recruitment of macrophages to the tumor area was increased, and has further facilitated the TGFβ-mediated activation of the tumor cells by macrophages through Notch (Figure 1(A2)).