LIF and glioma: Although generally considered a neuroprotector [19], TGF-β1 might be involved in the promotion and migration of glioma cells [20] and in selectively inducing self-renewal of the glioma-initiating cells via the SMAD-dependent activation of leukemia inhibitory factor (LIF) and the sequential activation of the LIF-Janus kinase-STAT pathway [21].