Mechanical Strain Regulates Osteoblast ProliferationThrough Ca2＋-CaMK-CREB Signal Pathway

Objective To investigate the effects of mechanical strain on Ca2＋-calmodulin dependent kinase（CaMK）-cAMP response element binding protein （CREB） signal pathway and proliferation of osteoblasts.Methods Using a four-point bending device, MC3T3-E1 cells were exposed to mechanical tensilestrains of 2500 μs and 5000 μs at 0.5 Hz respectively. The intracellular free Ca2＋ （[Ca2＋]i） concentration andcalmodulin activity were assayed by fluorospectrophotometry, CaMK II β, CREB, and phosphorylated（activated） CREB （p-CREB） were assessed by Western blot。