Practice question

MST1/2 and LATS1/2 are core kinases of Hippo signaling pathway controlling first lineage decisions during morula-to-blastocyst transition. In inner apolar cells Hippo is active: MST1/2 phosphorylate LATS1/2 which phosphorylate YAP, sequestering it cytoplasmically and permitting Nanog, Oct4 expression for inner cell mass fate. In outer polar cells Hippo is off, unphosphorylated YAP translocates to nucleus, interacts with TEAD4 to induce Cdx2 and Gata3 driving trophectoderm differentiation and blastocoel formation. Thus pathway does not regulate acrosome or capacitation but blastocyst patterning.