Fig. 3. Induction of MMP expression in the elongation stage. (A) Transcripts for MMP-2 and TIMP-2 in the differentiating C2C12 cells were measured by semi-quantitative RT-PCR. The results are normalized with G3PDH and presented as the mean ± s.e.m. (n = 3). (B) MMP-2 activity was monitored by gelatin zymography (upper panel). pro(gly); glycosylated form of proMMP-2, pro; proMMP-2, int; intermediate form, act; activated form, NCDM; none-conditioned differentiation medium. Expression patterns of MT1-MMP (middle panel) and tubulin (lower panel) were evaluated by western blot analysis. Open arrowhead indicates active MT1-MMP and closed one shows a major autolytically degraded fragment (Osenkowski et al., 2004). These results are representative one of three independent experiments.