- Transgenic mice with targeted inactivation of the Col2 alpha 1 gene for collagen II develop a skeleton with membranous and periosteal bone but no endochondral bone. Li, S.W., Prockop, D.J., Helminen, H., Fässler, R., Lapveteläinen, T., Kiraly, K., Peltarri, A., Arokoski, J., Lui, H., Arita, M. Genes Dev. (1995)