We analyzed Axl-Gas6 signal cascade using both UMUC3 and HT1376 cell lines, which are commercially purchasable UC cell lines. We used Western blotting analysis and immune-staining analysis. HT1376 is weak Axl-staining cell line and UMUC3 is a weak Axl-staining cell line. Commercially purchasable Axl kinase inhibitor, R428, had no cytotoxic ability in itself, but it blocks invasive capacity store-dependently in UMUC3 cell line. The protein expression of Axl and Gas6 by immunohistochemistry and its correlation with clinicopathologic features were investigated in surgical specimens obtained from patients who had been surgically treated for UTUC. Axl protein expression and its ligand Gas6 protein expression associate with each other, and both of them highly associated with worse prognosis of UTUC patients treated by radical nephroureterectomy.