MED29 is a component of the Mediator complex, a large multiprotein coactivator that bridges DNA-bound transcriptional regulators to the RNA polymerase II transcription machinery 1. The Mediator complex is conserved across eukaryotes and MED29 represents a consensus mammalian Mediator subunit identified through proteomic analysis 2. Comparative genomics reveals that MED29 (also known as Intersex) is homologous to yeast Med2 and is part of an ancient 17-subunit framework conserved across diverse eukaryotic species 3. Functionally, MED29 exhibits dual oncogenic and tumor suppressive characteristics in pancreatic cancer, where it can promote cell survival when highly expressed but suppress tumor growth when overexpressed in cells with low endogenous levels 1. MED29 is also involved in cancer progression through multiple pathways, including promotion of epithelial-mesenchymal transition and metastasis in oral squamous cell carcinoma via MAPK signaling 4, and activation by tRNA-derived fragments in non-small cell lung cancer 5. Additionally, biallelic variants in MED29 cause pontocerebellar hypoplasia with cataracts, demonstrating its critical role in neurodevelopment and cerebellar function 6. These findings highlight MED29's essential role in transcriptional regulation with significant implications for both cancer biology and neurodevelopmental disorders.