DKK1 and neoplasm: In contrast, MSCs have been shown to have anti-tumorigenic effects by releasing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) which selectively induces apoptosis in various cancers by inhibiting extracellular signal-regulated kinase-1/2 (ERK1/2) and protein kinase B (PKB)(also known as AKT) action and Dickkopf-related protein-1 (DKK-1) that block tumor growth by suppressing Wnt signaling [12,13,14].