PFN2 and osteosarcoma: An accurate prognosis prediction model based on 11 DEGs (MYCL, NDRG1, IFNLR1, C1GALT1C1L, ATP6V1G3, B3GALT4, MGAT1, PFN2, IL23A, ABCA7, and MAN2B1) between hot and cold osteosarcomas was constructed and validated.