C3 and urinary bladder cancer: Through analysis of the signaling pathway, we found increased ligand−receptor signaling between fibroblasts and T and B cells through the CXCL12-CXCR4 and CXCL2-CXCR2 axis in bladder cancer tissues as well as enhanced signaling from fibroblasts to myeloid cells, including signaling involving C3-CR2, C3-(ITGAX+ITGB2), C3-(ITGAM+ITGB2), and C3-C3AR1.