MAP3K2, mitogen-activated protein kinase kinase kinase 2, also known as MEKK2, belongs to the mitogen-activated protein kinase (MAPK) kinase kinase gene family, which is involved in regulating multiple MAPK signaling pathways. Endogenous MAP3K2 localized mainly to the cytosol of unstimulated HeLa cells and rat fibroblasts.The MAP3K2 gene is mapped to chromosome 2 by the International Radiation Hybrid Mapping Consortium. MAP3K2 is a major upstream activator of the JNK, MAPK cascade. MAP3K2 was identifies as 1 of 6 kinases that regulate different steps of the caveolar cycle. Silencing of MAP3K2 strongly reduced kiss-and-run dynamics, leading to an accumulation of caveolar structures at the cell surface without affecting caveolae coat assembly or clustering.