Micromolar GTP concentrations are able to improve skeletal muscle differentiation of C2C12 myoblasts. This action is mediated by the presence of specific binding sites for GTP related with the [Ca2+]i modulation (Pietrangelo et al., J Muscle Res Cell Motil. 2002, 23:107) and transient hyperpolarization (Pietrangelo et al., J. Physiol. 2005, in press). Data carried out from our experiments indicate that the presence of 500 uM GTP in the differentiating medium was capable to accelerate mitoses increasing the number of myoblasts and myotubes expressing myosin heavy chain proteins starting from two days of differentiation in presence of 500 uM GTP. The preincubation with 100 uM RB2, a P2Y inhibitor, or 200 nM CTX, a blocker of calcium intermediate potassium channel conductance, was also able to counteract the myogenic GTP action. We analysed the transcriptional profile of GTP-dependent myogenesis with high density oligonucleotide microarray technique and found different up-regulated genes, as Pax 7 and calcineurin. We validated our results using real time PCR. We conclude that the specific GTP-binding on cell membranes is capable, in C2C12 cells, to accelerate the myogenesis by Ca2+-correlated transcriptional factors.