Figure 3

MAPKs activation is required for MMP-9 expression in CRT-MG cells. (A) CRT-MG cells were treated with 500 ng/ml HIV-1 Tat protein for the indicated time. Whole cell lysates were analyzed for MAPK protein activation by Western blot analysis using phospho-specific antibodies against MAPK proteins. Equal lane loading was confirmed by detecting blots for total MAPKs. (B) Cells were pretreated with SP600125 (JNK inhibitor), SB203580 (p38 inhibitor), or PD98059 (ERK inhibitor) for 1 h before adding 500 ng/ml HIV-1 Tat protein for 6 h (MMP-9 mRNA) or 48 h (MMP-9 protein). MMP-9 mRNA expression was determined by RT-PCR. MMP-9 expression and activity was determined by Western blot and zymograpy.