Effect of PAR-2 agonists and tryptase inhibitor on L6 myoblast proliferation. L6 myoblast proliferation following treatment with either A) tryptase, D) trypsin or E) PAR-2 synthetic activating peptide SLIGKV, while control wells received medium with 1% FBS only. B) Tryptase was pre-incubated with APC-366 where control wells (not pre-incubated with the inhibitor) represent 0% inhibition (not shown). C) L6 myoblasts were incubated either with APC-366 or NS-398 alone for 48 h to test for the possible cell toxicity. Each data point represents the mean of five separate experiments (mean ± s.e.m). * Significantly different from control (CTRL) and # significantly different from APC-366 100 μM, P < 0.05.