FABP4 and breast cancer: We co-cultured mature adipocytes with MDA-MB-231 breast cancer cells for 24 h and found that the expression levels of adipocyte makers, including PPAR-γ, C/EBPα, and FABP4, were reduced, while the expression levels of preadipocyte marker PREF1 and two typical pro-inflammatory cytokines IL-6 and IL-1β were significantly enhanced (Figure 1C), suggesting that the adipocytes had been converted to CAAs.