C1QA and neoplasm: Tumor cells talked to macrophages through the ligand receptor pairs C1QB-LRP1, COL1A2-LRP1 and SERPINE2-LRP1, and macrophages talked back through SERPINA-LRP1, C1QB-LRP1 and C1QA-CSPG4; tumor cells talked to T-cells through COL1A2-ITGA1 and T cells talked back through GZMB-PGRMC1.