IL-6 is highly expressed in CAFs of breast cancer. a Human Cytokine Antibody Array Kits (RayBiotech) were applied to measure the content of 80 cytokines in the CM from diverse fibroblasts. The experiment was performed twice, and the results are shown in two rows. The CM of NAFs served as a control in each experiment. Cytokines upregulated in CAFs and indicated by colored boxes are IL-6 (red), IL-8 (green) and GRO (blue). GRO detects CXCL1, CXCL2 and CXCL3. The enclosed black frames indicate the positive controls, whereas the dashed boxes indicate the negative controls in each membrane. Abbreviations: NAF, non-cancer-associated fibroblast; FAD, fibroadenoma; PCF, paracancer fibroblast; CAF, cancer-associated fibroblast. L-A, luminal A; L-B, luminal B; Her2, Her2 positive; TNBC, triple-negative BrCA. b The dot intensity of the different cytokines was quantified by densitometry using ImageJ software (NIH, Bethesda, MD, USA) and normalized to the results. Columns: mean of triplicate experiments; bars: s.d. c ELISA results of secreted IL-6 from isolated fibroblasts from accessory breast (white), fibroadenoma (light gray), paracarcinoma (dark gray) and breast cancer (black). The experiments were performed at least three times independently with similar results. Columns, mean of triplicate experiments; bars, s.d. d The average concentration of IL-6 was quantified in three groups: accessory breast and fibroadenoma (light gray), paracarcinoma (dark gray) and breast cancer (black). Columns, mean of grouped IL-6 concentration; bars, s.d.