**6. Conclusions**

In this article, we described the impact of FGF-FGFR abnormalities on the development and/or the progression of PCa. Since we found the heterogeneity of PCa, it is important to clarify and understand various molecular mechanisms of PCa in order to determine the most appropriate therapeutic strategies.

**Author Contributions:** Conceptualization, J.T. and A.M.; methodology, J.T.; software, J.T.; formal analysis, K.G., R.Y., H.S., K.S. and H.N.; investigation, J.T., T.H., K.G., K.S. and H.N.; writing—original draft preparation, J.T.; writing—review and editing, J.T. and T.H.; visualization, S.I. and Y.S.; supervision, K.G., T.H., S.I., Y.S. and A.M.; funding acquisition, J.T. and A.M.

**Funding:** This research was supported by Grants-in-Aid for Scientific Research(C), gran<sup>t</sup> number 18K09134 from the Japan Society for the Promotion of Science.

**Conflicts of Interest:** The authors declare no conflict of interest.
