Effects of P311 on C2C12 cell proliferation and differentiation. (A) BrdU assay was performed on P311-infected and adenovirus-GFP control cells, as well as P311-transfected and vector only-transfected cells. For both approaches, P311 over-expression significantly increased cell proliferation. (B)P311-stably transfected C2C12 myotubes (differentiated for 9 days) were separately immunostained for desmin and MYH fast, along with DAPI nuclei staining. Under immunofluorescence, myotubes appeared less abundant in P311-transfected cells. (C) Fusion index quantification on immunostained images showed that P311-transfected cells resulted in less mytoube formation than control cells. Asterisks indicate statistical significance. BrdU assay and fusion index determination were analysed with SAS software, differences between pair-wise combinations of the least square means were tested for significance (*p < 0.05). Error bars were standard error, n = 3 replicates from 3 independent experiments.