In conclusion, using a CRISPR/Cas9 knockout library screen targeting tumor cells and macrophages respectively in a phagocytosis assay, we identified an interaction between Vtn expressed in cancer cells and C1qbp expressed on the plasma membrane of tumor-associated macrophages, which constrains macrophage phagocytosis and shifts macrophages more skewed toward the M2-like phenotype. Here, VTN is linked to neoplasm.