Fig. 7. ERK1/2 and p38 MAPK activation is suppressed in integrin-β1-null endoderm cells, and their inhibition abrogates vitronectin-induced GATA4 nuclear translocation and cellular maturation. (A) Endoderm cells isolated from 5-day EBs were either analyzed directly or cultured on vitronectin (Vn) for 2 days and then analyzed by western blotting. The activation of ERK1/2, p38 MAPK and Akt was detected using kinase phosphorylation-specific antibodies. (B) Integrin-β1-null endoderm cells were cultured on vitronectin and treated with the MEK1/2 inhibitor U0126 (10 µM), the p38 MAPK inhibitor SB203580 (10 µM), the PI3K inhibitor wortmannin (1 µM) or Akt1/2 inhibitor (10 µM). After 2 days, the cells were fixed and stained for Dab2 and GATA4. (C) The cells treated with the above kinase inhibitors were subject to western blot analysis for laminin-111 and nidogen.