Fig. 5. Apoptosis in PINCH1-null EBs. (A,B) Cell proliferation assessed by Ki67 staining (red) is seen in most epiblast and some endodermal cells from both wild-type and PINCH1-null EBs. (C,D) Immunostaining for cleaved caspase-3 (green) reveals apoptotic cells in the central portion of normal EBs leading to cavitation. Immunosignals were occasionally detected in the epiblast but rarely in the endoderm (C). PINCH1-null EBs have apoptotic endodermal cells with condensed nuclei (D). (E,F) Immunostaining for Ser473 phosphorylated form of PKB/Akt shows singly positive cells in the epiblast and endoderm layer both in sections derived from normal (E) and PINCH1-null EBs (F).