Figure 7

SRF activation suppresses reprogramming induced by ERK inhibition. (a) Luciferase assay of the SRF-reporter expressing GC5 cells infected with a lentivirus encoding iDsRed-VP64 or iSRF-VP64 after Dox treatment for 3 days. (b) Western blot analysis of SRF and reprogramming factor expression in a. (c) Reprogramming assay of GC5 cells in (A). After 24 h of infection with a lentivirus encoding iDsRed-VP64 or iSRF-VP64, MEF medium was changed to E6/LIF/Dox medium with or without PD03 (0.1 μM). (d) Western blot analysis of SRF expression in GC5 cells infected with a lentivirus encoding iSRF-VP64-HA. After infection, cells were treated with or without Dox (4 μg ml⁻¹). After incubation for 3 days, cells were lysed with kinase lysis buffer (R&D Systems). (e) ChIP assay for IEG promotor binding of SRF-VP64. GC5 cells were infected with a lentivirus encoding iSRF-VP64-HA for 24 h, replenished with fresh MEF medium and separately infected with retroviruses encoding DsRed, SRF-DN and SRF. Data are representative of two independent experiments and the mean of triplicates (per biological sample). In a and c, the results are the means±s.d. of three independent experiments (two-tailed, unpaired t-test; n=3). **P<0.01. ERK, extracellular signal-regulated kinase; IEGs, immediate-early genes; IP, immunoprecipitation; SRF, serum response factor.