MST1 and neoplasm: Mammalian sterile 20—like kinase 1 (Mst1) is an ubiquitously expressed serine/threonine kinase with a similarity to the Hippo kinase from Drosophila and it is a critical component of the Hippo signaling pathway, which regulates a variety of biological processes ranging from cell contact inhibition, cell growth, organ size control, apoptosis and tumor suppression in mammals [1], [2].