MAPK4 is an atypical mitogen-activated protein kinase that plays crucial roles in cellular proliferation, survival, and immune regulation. The protein exhibits oncogenic properties, being overexpressed in various cancers including glioma, triple-negative breast cancer, and prostate cancer, where it predicts poor prognosis 12. MAPK4 promotes tumor growth through multiple mechanisms: it activates AKT signaling independently of PI3K, enhances PDK1 protein synthesis, and stimulates the AKT/mTOR pathway to facilitate cell cycle progression and migration 231. This dual activation of AKT and PDK1 pathways contributes to cancer cell resistance against PI3K blockade therapy 3. In immune regulation, MAPK4 appears to have protective functions, as its deficiency leads to aberrant B cell activation in rheumatoid arthritis through disruption of the IRF4-SHIP1 signaling pathway, resulting in enhanced PI3K-AKT-mTOR signaling and increased IL-6 production 4. Clinically, MAPK4's role in cancer progression and therapy resistance makes it an attractive therapeutic target, with studies suggesting that co-targeting AKT and PDK1 could effectively treat MAPK4-high cancers 35.