Panx3 functions as a gap junction. (A) Real-time imaging of Ca²⁺ wave propagation. The Ca²⁺ wave was measured in cells loaded with Fluo-4 and NP-EGTA (caged Ca²⁺) by starting photolysis of NP-EGTA in a single cell using a flash of UV light. (a) pEF1/Panx3-transfected cells, but not pEF1-transfected cells, propagated Ca²⁺ waves to neighboring cells. (b) Inhibition of the Ca²⁺ wave propagation by CBX (gap junction inhibitor). (c) Apyrase, ATP receptor antagonist, did not inhibit Ca²⁺ propagation in pEF1/Panx3-transfected cells. (B) CBX inhibited C2C12 cell differentiation. (a) ALP staining. (b) Quantitative data from the ALP staining. CBX inhibited osteoblast differentiation in pEF1/Panx3-transfected cells (a and b). *, P < 0.05; **, P < 0.01. Error bars represent the mean ± SD; n = 3.