TGFB1 and osteosarcoma: MSCs also revealed tropism towards osteosarcoma cells, favoring their aggressiveness, through the expression of chemotactic factors, such as MCP-1, GRO-α and TGF-β1, and transdifferentiation to cancer-associated fibroblasts (CAFs), which further increased the cytokine levels in the tumor microenvironment and promoted transendothelial cell migration [192].