NCIt definition : An isoform of fibroblast growth factor receptor 2 where alternative splicing leads
to the expression of the IIIb exon encoding the second half of the third immunoglobulin-like
domain, which is located in the extracellular domain of these receptors. This variant
is expressed in epithelial lineage cells and has differential ligand binding activity
when compared to the IIIa and IIIc forms.;