Map2k4, also known as Mitogen-activated protein kinase kinase 4, is a key component in the mitogen-activated protein kinase (MAPK) signaling pathway. This pathway is crucial for regulating various cellular processes such as cell proliferation, differentiation, apoptosis, and stress response. It functions by phosphorylating and activating downstream MAP kinases, thereby transmitting extracellular signals from the cell membrane to the nucleus [2].

However, the provided references do not contain direct information on Map2k4 knockout (KO) or conditional knockout (CKO) mouse models. There is more information regarding other components of the MAPK pathway, like BRAF and MAP2K1 in relation to diseases such as Erdheim-Chester disease (ECD) [1]. In ECD, over 80% of patients have mutations activating the MAPK pathway, mainly BRAFV600E (57%-70% of cases) and MAP2K1 (close to 20%) [1].

In conclusion, while the references lack KO/CKO mouse model data for Map2k4, its role as an essential part of the MAPK pathway is clear. Understanding Map2k4's function is crucial as the MAPK pathway is implicated in numerous disease conditions, as seen with the related MAPK-activating mutations in ECD [1,2].