C1QBP and neoplasm: To further confirm the binding of tumor-derived Vtn with C1qbp on macrophage plasma membranes, we co-cultured the control Raw264.7 or C1qbp-knockdown Raw264.7 cells, in which C1qbp was hardly detectable (Figure 3E), with the conditional medium (CM) from 4T1 cells expressing Myc-tagged Vtn (Figure 3F).