MBIP (MAP3K12 binding inhibitory protein 1),also known as MAPK upstream kinase (MUK)-binding inhibitory protein,is a 344 amino acid nuclear and cytoplasmic protein that assists in the activation of the JNK pathway by inhibiting ZPK activity. Ubiquitously expressed,MBIP is found at high levels in lung and heart and is one component of the ADA2A-containing complex (ATAC) in conjunction with ADA3,GCN5,CDC101,TADA2L,WDR5,YEATS2,DR1 and CRP2BP.