Figure 5.

Internalization of ¹²⁵I-FGF into cells deficient in FRS2α. (A) MEFs deficient in FRS2α (■) ectopically expressing wild-type (X) FRS2α or the 2F (○), 4F (▵), or 6F (●) FRS2α mutants were assayed for ¹²⁵I-FGF internalization as a function of time. The graph presented represents the average of quadruplicate experiments. (B) MEFs deficient in FRS2α ectopically expressing wild-type FRS2α or the 4F FRS2α mutant were treated with FGF and cycloheximide for the times indicated. Cell lysates were subjected to immunoprecipitation with anti-FGFR Abs followed by immunoblotting with anti-pTyr or anti-FGFR Abs.