LY6D and osteosarcoma: However, it is still unknown whether LY6D functionally contributes to the senescence process because our previous study has shown that ectopic expression of LY6D in osteosarcoma U2OS cells had little effect on senescence induction as determined by colony-forming assay and by senescence-associated β-galactosidase (SA-β-Gal) staining, an established marker of senescence.