FGFR4 and β-Klotho in Metastatic Prostate Cancer by Derek LaMar Shenefelt Fibroblast growth factors and fibroblast growth factor receptors have been associated with the aggressiveness and progression of Prostate Cancer (PCa). Also, β-Klotho is a known co-receptor with FGFR4 for FGF19 in the liver however, the role of this co-receptor pair remains unclear in the setting of PCa. I demonstrated that FGFR4 and KLB mRNA and protein are highly expressed in PCa cells when compared to bone marrow stromal cells, a common site of metastasis. I also provide support for the association of FGFR4 and KLB in PCa, suggesting a functional co-receptor pair capable of altering cellular signaling. FGFR4-KLb may also provide some level of protection to PCa cells from chemotherapeutics. This analysis of FGFR4 and KLB expression and signaling in PCa has provided novel insights into phenotypic alterations during PCa progression while also providing new avenues of study to further explore the role and importance of this exciting co-receptor complex.