HSV-1 (McKrae strain) was propagated and viral titers were determined in Vero cells as described previously . The supernatant from normal Vero cells culture was used as a control (Mock). Before infection or transfection, BCBL-1 cells were incubated in serum-free
RPMI-1640 medium for a maximum inducibility of KSHV replication . 2.2. Antibodies and reagents Anti-phospho-STAT3 (Tyr705) rabbit monoclonal antibody (mAb), anti-phospho-PI3K p85 (Tyr458)/p55 (Tyr199) rabbit polyclonal antibody (pAb), anti-phospho-AKT (Ser473) mouse mAb, anti-phospho-GSK-3β check details (Ser9, GSK: glycogen synthase kinase) rabbit pAb, anti-phospho-c-Raf (Ser338) rabbit pAb, anti-phospho-MEK1/2 (Ser217/221, MEK: MAPK-ERK kinase) rabbit pAb,
anti-phospho-ERK1/2 MK-8931 mouse (Thr202/Tyr204) rabbit mAb, anti-STAT3 rabbit pAb, anti-PI3K p85 rabbit pAb, anti-GSK-3β rabbit mAb, anti-c-Raf rabbit pAb, anti-MEK1/2 rabbit pAb, anti-Flag M2 mouse mAb, anti-hemagglutinin (HA) rabbit mAb and LY294002 (PI3K inhibitor) were purchased from Cell Signaling Technologies (Beverly, MA, USA). Anti-PTEN (PTEN: phosphatase and tensin homologue deleted on chromosome ten) mouse mAb, anti-β-actin mouse mAb, anti-α-Tubulin mouse mAb, anti-GAPDH mouse mAb and horseradish peroxidase (HRP)-Epigenetics inhibitor conjugated goat anti-mouse/rabbit IgG were obtained from Santa Cruz Biotechnologies (Santa Cruz, CA, USA). Anti-AKT rabbit pAb were obtained from BioVision (Mountain view, CA, USA). Anti-ERK1/2 rabbit pAb were obtained from Shanghai Kangchen Biotechnologies (Shanghai, China). Piceatannol (JAK1 inhibitor) was purchased from BIOMOL Research Laboratories Inc. (Plymouth Meeting, PA, USA). Both anti-phospho-STAT6 (Tyr641) mouse mAb and Peptide II (ERK inhibitor) were obtained from Calbiochem (Darmstadt, Germany). Anti-STAT6 rabbit pAb was purchased from Bethyl Laboratories Inc. (Montgomery, TX, USA). Anti-KSHV ORF59 mAb and viral IL-6 (vIL-6) rabbit pAb were obtained from Advanced BCKDHA Biotechnologies Inc. (Columbia,
MD, USA). Anti-KSHV Rta (replication and transcription activator) antibody was generated by immunization of rabbits with ORF50 peptide (amino acids 667-691) . 2.3. Western blot analysis After infection, cells were harvested and lysed in RIPA buffer containing protease and phosphatase inhibitors. 60-80 μg of proteins were loaded onto sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), transferred to polyvinylidene fluoride (PVDF) membrane. The membrane was incubated with diluted primary Abs for overnight at 4°C, and then incubated with HRP-conjugated species-specific second Abs for 1 h at 37°C. Proteins were visualized by enhanced chemiluminescence (ECL) reagents (Cell Signaling Technologies) according to the manufacture’s instructions. 2.4.