Figure 1

MEK/ERK pathway is required for E2F4 nuclear translocation and G1/S phase transition in HIEC. A. Subconfluent HIEC were serum-deprived for 36 h, treated or not (DMSO) during 10 min with 20 μM U0126 and then stimulated during 30 min or 24 h with 5% FBS. Thereafter, cells were lysed and proteins were analyzed by SDS-PAGE for Western blot analysis of the expression of ERK2, pRb, cyclin D1, p27, phosphorylated ERK1/2 and β-actin. B. HIEC grown on coverslips were serum-deprived during 36 h and then stimulated with 5% FBS with or without 20 μM U0126 (or DMSO). After 24 h, cells were fixed using 3% paraformaldehyde, permeabilized and analyzed by immunofluorescence for E2F4 expression.