Consistently, our H&E staining data showed that the femurs obtained from 1.5-, 3.5- and 7-month-old Ctsk-Cre;Trp53f/f/Rb1f/f mice exhibited more expansive osteosarcoma osteoid lesions in the cortical bone with increasing age (Figure 1C). Here, CTSK is linked to osteosarcoma.