Mitogen-activated protein kinase kinase 4 (MAP2K4) (MEK4)

Mitogen-activated protein kinase kinase 4 (MEK4), also known as MAP2K4 or MKK4, is a dual-specificity protein kinase that acts as a central node in the mitogen-activated protein kinase (MAPK) signaling architecture [9, 13]. It is primarily responsible for phosphorylating and activating the c-Jun N-terminal kinase (JNK) and p38 MAPK pathways in response to various stimuli, including environmental stress, pro-inflammatory cytokines, and growth factors [2, 13]. In the context of oncology, MEK4 is frequently overexpressed in aggressive malignancies such as prostate, pancreatic, and ovarian cancers, where it facilitates tumor cell invasion and metastasis [4, 9]. Interestingly, MEK4 also functions as a potent inhibitor of hepatocyte proliferation, making it a high-interest target for regenerative medicine to treat acute and chronic liver failure [1, 12]. Therapeutic strategies involving MEK4 focus on small-molecule inhibitors that block its ATP-binding site or allosteric pockets to modulate downstream stress signaling [1, 2]. Clinical candidates like HRX215 are currently being evaluated for their ability to enhance liver regeneration following surgery or injury [1, 9]. However, drug development faces challenges such as achieving selectivity over other MEK family members and managing complex feedback loops that can reactivate survival pathways in cancer cells [5, 17].

Other names

MAP2K4MKK4JNKK1SEK1SKK1SERK1MAPKK4PRKMK4SAPKK1

MEK4 inhibitors primarily function through ATP-competitive binding to the kinase domain, thereby preventing the dual phosphorylation of downstream targets JNK and p38 [1, 2]. Some inhibitors may also act through allosteric or covalent mechanisms to induce conformational changes that reduce enzymatic activity [2]. By obstructing the MEK4-mediated activation of the stress-activated protein kinase (SAPK) pathway, these drugs can induce apoptosis in cancer cells or promote pro-regenerative signaling in hepatocytes [2, 9].