LIF and osteosarcoma: In the LIF/gp130/STAT3 pathway, the relationship with CSCs has not been directly demonstrated; however, recent evidence indicates that LIF functions as a growth factor to promote the growth and invasion of osteosarcoma [64] and that LIF/gp130/STAT3 signaling via autocrine and paracrine mechanisms is upregulated in tumors [65,66,67].