Changes in vascularization and signal transduction in Fgfr-1^−/− embryoid bodies. (A) Increased vessel formation in the absence of exogenous growth factors in Fgfr-1^−/− embryoid bodies compared with Fgfr-1^+/−. Bars represent 100 μm. (B) Analysis of serine/threonine kinases Erk and Akt and their phosphorylated counterparts by immunoblotting. Phosphorylation of Akt was evaluated in the absence (control) and presence (LY294002) of the PI3K inhibitor (10 μM) in Fgfr-1^+/− and Fgfr-1^−/− embryoid bodies on day 8 of differentiation. Quantification shows fold induction of phosphorylated Akt/Akt protein (pAkt/Akt) in relation to pAkt/Akt in the +/− control (set to 1). The figure shows results representative of several individual experiments. Vertical lines indicate gel lanes repositioned from the same blot, whereas horizontal lines mark the boundary between consecutive blots for pErk/Erk and pAkt/Akt, respectively. (C) Immunofluorescence staining of pAkt (green) and CD31 (red) in Fgfr-1^−/− and Fgfr-1^+/− embryoid bodies at day 8. Bars represent 20 μm.