TBX3 and fibrosarcoma: Rhabdomyosarcomagenesis involves, in part, the prolonged activation of serine/threonine kinases such as AKT [60], and we have previously shown that AKT1 and AKT3 phosphorylation stabilizes the TBX3 protein in chondrosarcoma/fibrosarcoma and melanoma, respectively [50,71].