To identify the cytokines responsible for activating chemoresistance-inducing fibroblasts, the cytokine profiles of tumor CM from chemosensitive breast cancer with rare CD10+GPR77+ CAFs and from chemoresistant breast cancer with abundant CD10+GPR77+ CAFs were analyzed using a RayBio Human Cytokine Antibody Array (Fig. 1D). The gene discussed is C5AR2; the disease is breast cancer.