NTRK1 and neoplasm: In the present study, we showed that 1) CD44v3 mimetic peptide 4, which did not inhibit TrkA phosphorylation but blocked TrkA/CD44v3 complex formation, impeded tumor growth and metastases and that 2) RhoA activation was probably dependent not only on TrkA phosphorylation but also on complex formation by recruiting RhoA, as indicated by experiments in which we used kinase-dead TrkA (Fig. 8).