Two isoforms of CaMKK, CAMKK1 (CaMKK alpha) and CAMKK2 (CaMKK beta) are expressed in the brain and involved in signaling downstream of the NMDA receptor (Schmitt et al. 2005, Mairet-Coello et al. 2013). CAMKK1 (Lee et al. 2010) and CAMKK2 (Kylarova et al. 2018) become catalytically active upon binding to the calcium-bound calmodulin (CALM1:4xCa2+). Calcium-bound calmodulin needs to translocate to the nucleus for CaMKK activation that precedes CAMK4 phosphorylation in glutamatergic neurons (Ma et al. 2014).