MO25, also called CAB39 (calcium binding protein 39), forms a heterotrimeric complex with an LKB1 (ste20-related adaptor and liver kinase B1) and this complex acts as a major upstream regulator of AMPK-mTOR pathway in mammalian cells. It is well known that AMPK exhibits a number of functions, including the regulation of metabolism, cell polarity, and autophagy in mammalian cells.