Eat-me signals: keys to molecular phagocyte biology and "appetite" control.

Hundreds of billions of cells undergo apoptosis in our body everyday and are removed by immunologically silent phagocytosis to maintain tissue homeostasis. Impairments in phagocytosis result in autoimmune and/or degenerative diseases. Eat-me signals are the key to the recognition of extracellular cargos and the initiation of the phagocytosis process by activating phagocytic receptors and signaling cascades, and are convenient targets for therapeutic modulation. Despite their importance, eat-me signals and other phagocytosis players are mostly identified on case-by-case basis with daunting challenges. This Commentary focuses on our latest knowledge of the extracellular players, highlights our approaches to systematically map unknown pathways by functional genetic and proteomic technologies, and discusses future direction to unravel the mystery of molecular phagocyte biology.