GDF15 and neoplasm: GDF15, also known as macrophage inhibitory cytokine-1 or nonsteroidal anti-inflammatory drug-activated gene, was first isolated in macrophages based on its increased mRNA expression after cytokine stimulation.[7] Endogenous expression of GDF15 is regulated by several tumor-related pathways, including p53/DEC1, GSK-3β and EGR-1.[8–12] Similar to other TGF-β superfamily cytokines, GDF15 is synthesized as a precursor protein.