Figure 8. Both CPV TK gene expression and DNA replication did not rely on MEK/ERK, but sustained ERK1/2 phosphorylation was dependent on viral DNA replication.

Cells were mock-infected or infected with CPV at an MOI of 5.0 in either the absence or the presence of 50 μM PD98059 (PD) (A and B) or Ara C (40 μg/ml) (C) for the times shown. (A) Viral RNA was isolated as described in the Experimental section, blotted and hybridized with ³²P-labelled CPV TK probe. (B) Viral DNA was isolated, dot-blotted and hybridized with ³²P-labelled CPV DNA. Results are means±S.D. of the quantification of duplicate samples for each time point. No statistically significant difference was seen between samples with or without PD98059 (Student's non-parametric two-tailed t test). (C) Whole-cell lysates were immunoblotted with anti-phospho-ERK1/2. Results were consistently confirmed in three independent experiments.