GDNF and neoplasm: Macrophages with SACC-83 CM: M2 marker CD163↑, CD206↑ (FC), M2 marker Arg1↑, IL-10↑, M1 marker TNFα↓, IL-1β↓ (RT-PCR), GDNF expression↑ (RT-PCR, WB, ELISA), in presence of RS504393: M1 markers Arg1 and IL-10↓ (RT-PCR), murine SACC-83 xenograft model + RS504393: tumor associated M2 macrophages CD163↓ (immunohistochemical cell counts)