IL6 and cancer: To investigate the relationship between CAFs in the TME and serum IL-6, we analyzed three groups with varying amounts of fibroblasts: cancer cells alone (Colon26), co-inoculated cancer cells and fibroblasts (Colon26 + 1NIH/3T3, 1:1), and co-inoculated cells with Colon26 + 2NIH/3T3 (1:2).