Receptor for basic fibroblast growth factor. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] During tissue displacement in the early bud, transiently present ubiquitously. A few hours later, coincident with the acquisition of organiser properties by the bud tip, a few cells in the apical tip express the gene strongly. About 20 hours after the onset of evagination, expression is switched on in a ring of cells surrounding the bud base, and shortly thereafter vanishes from the apical expression zone. The basal ring persists in the parent during tissue contraction and foot formation in the young polyp, until several hours after bud detachment. Inhibition of bud detachment by head regeneration results in severe distortion, disruption or even complete loss of the well-defined ring-like expression zone. Belongs to the protein kinase superfamily. Tyr protein kinase family. Fibroblast growth factor receptor subfamily.