The Hippo signaling pathway , also known as the Salvador-Warts-Hippo
(SWH) pathway , is a signaling pathway that controls organ size in
animals through the regulation of cell proliferation and apoptosis. The
pathway takes its name from one of its key signaling components—the protein
kinase Hippo (Hpo). Mutations in this gene lead to tissue overgrowth, or a
"hippopotamus"-like phenotype.
A fundamental question in developmental biology is how an organ knows to stop
growing after reaching a particular size. Organ growth relies on several
processes occurring at the cellular level, including cell division and
programmed cell death (or apoptosis).