To explore whether the Hippo pathway plays a role in this primary osteosarcoma mouse model, we first isolated the primary osteosarcoma cells and normal cortical bone cells from Ctsk-Cre;Trp53f/f/Rb1f/f mice and age-matched controls, respectively (Figure 2A), and analyzed YAP/TAZ expression. This evidence concerns the gene CTSK and osteosarcoma.