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. 1999 Apr 27;96(9):4995–5000. doi: 10.1073/pnas.96.9.4995

Figure 5.

Figure 5

Viral peptides recruit ErbB-2. (A) Phosphorylation of ErbB-2 by viral peptides [vaccinnia virus growth factor (VGF), Myxoma virus growth factor (MGF), and SFGF] and antibodies (L87, L431) was examined as described in the legend to Fig. 1. (B) IL-3-deprived D23 cells were stimulated by viral peptides in the presence (+L26) or absence (−L26) of a class II mAb to the human ErbB-2 (Left). Cells singly expressing ErbB-2 (D2) or ErbB-1 (D1) served as negative and positive controls for ligand activity, respectively. Proliferation induction was determined by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay as described in the legend to Fig. 2. For control of endogenous proliferation signals, we incubated cells with IL-3. (C) The effect of ErbB-2 on downstream activation by SFGF was examined in cells that do (T47D) or do not (T47D-5R) express ErbB-2 on their surface. A time response of activation was detected in whole cell lysates by immunoblotting with an antibody against activated MAPK. The amount of ErbB-2 was verified by immunoblotting the upper part of the membrane with an antibody against the receptor.