Effects of single or multiple Y→F substitutions on TEL-FGFR3 activity. Ba/F3 cells transduced with empty retroviral vector were included as a control. (A) Schematic diagram of TEL-FGFR3 fusion tyrosine kinase that contains an N-terminal TEL PNT dimerization domain and a cytoplasmic FGFR3 intracellular tyrosine kinase (TK) domain. (B) Effects of diverse tyrosine mutations on TEL-FGFR3 transforming activity in Ba/F3 cells in cell viability assay. The relative cell viability was normalized to the viability of cells stably expressing TEL-FGFR3 control. Data presented are mean ± standard error (n = 3). (C) Autophosphorylation of distinct TEL-FGFR3 variants assessed by specific phosphotyrosine antibody. Expression of distinct TEL-FGFR3 mutants was examined. (D) Tyrosine phosphorylation of PLCγ, PI3K, and STAT5 by TEL-FGFR3 variants. Mutation Y760F abolishes TEL-FGFR3–dependent phosphorylation and activation of PLCγ.