Especially regarding osteosarcoma, due to its high genetic heterogeneity, conditional activation of oncogenes or deletion of several suppressor genes known to be implicated in tumor initiation and progression, such as p53, RB, p14 alternative reading frame (p14ARF), p16INK4a, neurofibromatosis type 2 (NF2), p27, protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A), and p21CIP, is a common method used to construct transgenic mouse models. The gene discussed is RB1; the disease is osteosarcoma.