Herein, we demonstrated for the first time that macrophages play an essential role in the potent pro-tumor effect of GC-MSCs; in turn, GC-MSCs induce the polarization of macrophages into the M2 subtype through secreting IL-6 and IL-8 via the JAK2/STAT3 signaling pathway. The gene discussed is CXCL8; the disease is neoplasm.