In addition to the osteopenia developed by Cola1(I)-Cre; Cx43−/fl mice, Cx43 deficiency in osteoblasts attenuated the anabolic response to in vivo mechanical loading.98 After being subjected to a three-point bending protocol for two weeks, the loaded tibiae from Cola1(I)-Cre; Cx43−/fl mice showed significantly reduced mineral apposition and bone-formation rates relative to those of control Cx43+/fl mice. The gene discussed is GJA1; the disease is Osteopenia.