Figure S3.

Loss of PTPN14 reduces degradation of EGFR but does not affect EGFR ubiquitination. (a) Representative Western blot showing EGFR levels (top panel) and total protein (represented by vinculin levels; lower panel) in siCtrl and siPTPN14 cells, pretreated with cycloheximide for 30 min before stimulation with 20 or 100 ng/ml EGF for the indicated times. (b–d) Ubiquitination of EGFR in control (siCtrl) or PTPN14 knockdown (siPTPN14) cells. Representative Western blots of PTPN14 expression from n = 3 independent experiments (b) and Western blots showing EGFR ubiquitination in cells transiently transfected with HA-ubiquitin and stimulated with 20 ng/ml (c and d) or 100 ng/ml (d) EGF for the indicated times, detected by EGFR immunoprecipitation (IP) immunoblotted with anti-HA or anti-ubiquitin Ab (upper panel) or with anti-EGFR Ab (lower panel). Arrowheads indicate position of EGFR.