| A yeast two hybrid analysis has shown that the juxtamembrane region of FGF receptor 3 ( FGFR 3 ) interacts with the cytoplasmic domain of EphA 4 , which is a member of the largest family of receptor tyrosine kinases . ^^^ Complex formation between the two receptors was shown to be mediated by direct interactions between the juxtamembrane domain of FGFR 1 , FGFR 2 , FGFR 3 , or FGFR 4 and the N terminal portion of the tyrosine kinase domain of EphA 4 . ^^^ |