MED22 (mediator complex subunit 22) is a component of the Mediator complex, a crucial transcriptional coactivator that regulates RNA polymerase II-dependent gene transcription 1. The protein functions as part of the head module of the Mediator complex, which adopts a crocodile-like structure with multiple mobile elements that facilitate interactions with RNA polymerase II and its carboxy-terminal domain 1. In kidney physiology, MED22 plays a critical role in maintaining podocyte health, as podocyte-specific knockout mice develop progressive glomerular disease, intracellular vacuole formation, and premature death due to renal failure 2. The protein has significant clinical relevance in cancer biology, where elevated MED22 expression is associated with poor prognosis in hepatocellular carcinoma and correlates with immune cell infiltration 3. In bladder cancer, MED22 functions as a super-enhancer-associated oncogene that can be therapeutically targeted through CDK7 inhibition 4. Additionally, MED22 alternative splicing events serve as prognostic biomarkers in skin cutaneous melanoma 5, and the protein shows differential expression patterns across carotid body tumor classifications 6. These findings establish MED22 as both a fundamental transcriptional regulator and a potential therapeutic target in multiple diseases.