TP53 and osteosarcoma: Compound cross with p53-deficient mice (Prx1Cre-mediated p53 deletion) synergized in osteosarcoma formation.12, 13 Furthermore, data from six independent laboratories presented 16 different Cre-mediated transgenic approaches to generate an Ewing Sarcoma mouse, which failed owing to high apoptosis and toxicity upon EF expression in multiple cell types.14