FIG. 4.

Detection of mRNA expression of MMP-1, -2, and -9 in mock- and KSHV-infected HUVEC at different times postinfection by RT-qPCR. Total cellular RNA isolated at different time points following mock or KSHV infection was examined by RT-qPCR with respective specific primers for MMP-1 (A), -2 (B), and -9 (C). RT-qPCR for GAPDH was carried out to calibrate the amount of RNA input. The numbers at the tops of the bars are fold increases of KSHV-infected cultures over mock-infected cultures at the same time point. (A) MMP-1 transcript was expressed at low levels in mock-infected cells but was upregulated following KSHV infection at 6 hpi, which was sustained for up to 24 hpi. (B) MMP-2 transcript was strongly expressed in mock-infected cells. KSHV infection did not alter the expression of MMP-2 transcript before 6 hpi but downregulated its expression at and after 12 hpi. (C) MMP-9 transcript was not detectable in mock-infected cells but was significantly upregulated following KSHV infection at 6 hpi, which was sustained for up to 48 hpi. The fold increase was calculated either with the transcript expression levels at 0 hpi set as 1 (A and B) or with the first detectable time point set as 1 (C).