Defective cellular trafficking causes loss of collagen-induced signalling for the DDR2-S823Cfs* mutant. Full-length untagged wild-type DDR2 or S823Cfs* mutant were transiently expressed in HEK-293 cells. (A) Cells were stimulated for 90 min at 37°C with rat tail collagen I at the indicated concentrations (in μg/ml). Cell lysates were analyzed by SDS–PAGE and Western blotting. The blots were probed with anti-phosphotyrosine (anti-PY) monoclonal antibody 4G10 (upper blot) or polyclonal anti-DDR2 antibodies (lower blot). (B) Cell lysates were treated with Endoglycosidase H (H) or left untreated (-) for 3 h at 37°C and analyzed by SDS–PAGE and Western blotting. The blot was probed with polyclonal anti-DDR2 antibodies. The positions of molecular markers (in kDa) are indicated. The experiments were carried out twice with very similar results.