GAS6 and neoplasm: Growth arrest-specific 6 (GAS6) (51), Wnt5α (52), leukemia inhibitory factor (LIF) (53) and TGF-β family members such as bone morphogenic protein 7 (BMP7) (54) and transforming growth factor beta 2 (TGFβ2) (55, 56) were shown to exert quiescence of DTCs at the BM niche, whereas, bone morphogenic protein 4 (BMP4) was shown to promote tumor dormancy in the lung (57).