“…Indeed, based on the "seed and soil' theory of Paget, it is now well recognized that osteosarcoma, like other cancers, requires an adequate local microenvironment for its development [11,12]. This microenvironment can provide all metabolites and factors for the control of proliferation, drug resistance, dissemination or/and dormancy of osteosarcoma cells [5,[13][14][15]. Then, the pressure exerted by microenvironment may be responsible for a specific selection of osteosarcoma cells with predominant specificities such as a high quiescent or a proliferative profile.…”