MAP3K1 and leukemia: BAALC can act as a scaffolding protein in leukemia cells (16), and can induce cell cycle progression of leukaemia cells by interacting with MEK kinase-1 (MEKK1), which inhibits the interaction between extracellular signal-regulated kinase (ERK) and MAP kinase phosphatase 3 (MKP3), thereby leading to sustained ERK activity.