FIG. 3.

Effects of inhibitors on NeuT induction of cyclin D1. To examine the intracellular signaling pathways involved in Neu induction of the cyclin D1 promoter, the −1745CD1LUC reporter was introduced into MCF7 cells with the NeuT expression vector. (A) Cotransfection experiments were conducted using increasing amounts of dominant negative expression vector, and the inhibition of Neu-induced promoter activation is shown as percent activity. Comparison was made between the effect of the dominant negative mutants for N17Ras, N17Rac, or N19Rho and equal amounts of empty expression vector cassette. (B) The chemical inhibitors of the MEK/ERK pathway (PD098059) (n = 8) and the p38 pathway (SB203580) (n = 8) were added to the culture medium and compared with equal volumes of DMSO vehicle. The expression vector encoding the inhibitor of JNK signaling (JIP-1) (n = 4) for each concentration of plasmid is shown compared with equal amounts of empty expression vector cassette. Inhibition is significant at P < 0.05.