G-CSF stimulated degradation of the wild-type (WT) and ▵716 mutant G-CSFR. (A) Confluent monolayers of COS-7 cells, transfected with the wild-type (WT) G-CSFR alone, mutant ▵716 receptor alone, or cotransfected with both the WT and ▵716 receptors (WT/▵716), were incubated for 1 hour in DMEM containing [³⁵S] methionine and [³⁵S] cysteine. Thereafter, the cells were incubated in DMEM containing 1nmol/L G-CSF and unlabeled methionine and cysteine for 0 to 8 hours. The cells were lysed, immunoprecipitated with antibody to the aminoterminus of the G-CSFR, and analyzed by SDS-PAGE followed by autoradiography. Both receptor forms are glycosylated to more mature forms (arrows). (B) The autoradiographs from (A) were analyzed by densitometry. Data are expressed as the fold-change compared to time 0.