4T1-M CM and 4T1-N2 CM differentially increased the expression of other TAM activation markers. RAW 264.7 or PEM cells were treated with 4T1-M CM or 4T1-N2 CM for 24 h. (A-C) The mRNA expression levels of TAM activation markers (IL-6, Fra-1 and TGF-β) in RAW 264.7 cells were measured by quantitative real-time PCR. (D and F) The protein levels of TAM activation markers (Fra-1, PD-L1 and MMP-9) were measured by western blot analysis. (E) The mRNA expression level of Fra-1 in PEM was measured by quantitative real-time PCR. The results are presented as the mean ± SEM. The data are representative of at least three independent experiments. *P < 0.05, ***P < 0.001, ****P < 0.0001.