Functional analysis of FGFR1 variants. (A, B and C) Signalling activity of WT and altered FGFR1 receptors in L6 myoblasts. Plotted are means±s.e.m. of three independent experiments. p.Ser107Leu (A) and p.Pro772Ser (B) variants had normal signalling activity, while p.Arg448Trp had reduced maximal signalling activity (**statistically significant (P<0.01)) (C). (D) Western blot analysis of CHO cells transiently transfected with empty vector (EV), FGFR1 WT or p.Arg448Trp constructs. UT, untreated; EH, EndoH treated; PG, PNGase treated. (E and F) Densitometry analysis of total protein and maturation levels of WT and p.Arg448Trp receptors. Plotted are means±s.e.m. of three independent experiments. (G) Cell-surface expression levels of WT and p.Arg448Trp receptors assessed in live transiently transfected COS-7 cells. Plotted are means±s.e.m. of five independent experiments (*statistically significant (P<0.05)).