The Proliferation and differentiation of adult stem/progenitor cells into specific lineages should be precisely regulated during organ development.Hippo pathway and its effector Yap have been investigated in liver size control and carcinogenesis.Mice with liver specific deletion of genes (Nf2, Mst1/2, Sav1) show histologically distinct phenotypes with more or less expansion of liver progenitor cells and subsequent liver cancer development.Interestingly, it has been reported that YAP activation in vivo dedifferentiates adult hepatocytes into progenitor-like cells.However, the role of Hippo signaling in cell fate determination and differentiation of hepatic stem/progenitor cells are poorly understood during liver development.By using mice with liver-specific deletion of Lats1 and Last2, we demonstrate that the Hippo signaling differentially affects the cell fate determination and differentiation of liver cell types during development.