CD74 and cancer: Thereafter, MC38 cancer cells showed the decreased expression level of CD74 on the cell surface and downregulated MIF downstream signaling pathway during incubation with serum in rSmeg-hMIF-hIL-7 compared with Smeg, indicating that MIF, which plays a crucial role in cancer cell proliferation, was neutralized by anti-MIF IgG in the serum (figure 5B and C).