FIG. 11.

Effect of ERK inhibitor U0126 on the activation of MAPK-dependent transcription factors. (A) Monitoring MAPK-regulated transcription factor activity. Nuclear extracts prepared from uninfected HFF cells and HFF cells infected with KSHV for 120 min were tested for the activity of MAPK-regulated transcription factors by incubating the nuclear extracts to the plate-immobilized oligonucleotides containing various transcription factor-specific sites, followed by ELISA with phosphorylation-specific antibodies to the respective transcription factors. For competition, soluble oligonucleotides containing various transcription factor-specific sites (wild type) or its mutant form were added to the nuclear extracts. Positive controls provided for each transcription factor were used simultaneously. The histogram represents the activation levels of c-Jun, STAT1α, MEF2, c-Myc, ATF-2, and c-Fos in the nuclear extracts from KSHV-infected HFF cells. Data represent the average ± standard deviation of three experiments, and values shown here are after the subtraction of values from uninfected cells. (B) Histogram depicting the percent inhibition of DNA binding of MAPK-dependent transcription factors in nuclear extracts from HFF cells pretreated with U0126 and then infected with KSHV for different time points. Percent inhibition was calculated with respect to the DNA binding activities in KSHV-infected HFF cells without U0126 pretreatment. Data represent the average ± standard deviations of three experiments.