MKKK -> MKKK_P MKKK_P -> MKKK MKK -> MKK_P MKK_P -> MKK_PP MKK_PP -> MKK_P MKK_P -> MKK MAPK -> MAPK_P MAPK_P -> MAPK_PP MAPK_PP -> MAPK_P MAPK_P -> MAPK