Fig. 6.

EPO induces the activation of extracellular signal-regulated kinase (ERK) via N-linked glycosylation through the initial activation of HER2

Western blots of 16HBE14o protein from cells treated with or without EPO (4 μg/ml) at the indicated times. Some were pre-treated with the inhibitor AG825 (10 μM, 2 h) or the endoglycosidase PNGase F (2 U/ml, 1 h) (see legend) and probed with a rabbit anti-human pERK antibody. The graphs show the fold change in pERK expression levels in response to EPO treatment compared to untreated cells in the absence or presence of inhibitors at the indicated times. (n = 3, mean ± sem; *p < 0.05, **p < 0.01, ***p < 0.001). The blots shown are representative of 3 similar experiments. Protein levels of total ERK remain unchanged in the presence of EPO and the various inhibitors studied (data not shown).