JMJD7 is a bifunctional Fe(II) and 2-oxoglutarate-dependent oxygenase with dual enzymatic roles in gene regulation and protein modification. As an endopeptidase, JMJD7 cleaves histone N-terminal tails at positions adjacent to methylated arginine or lysine residues, preferentially recognizing monomethylated and dimethylated arginines on histones H2, H3, and H4 1. This cleavage generates 'tailless nucleosomes' that may trigger transcription elongation 1. Following initial proteolytic cleavage, JMJD7 exhibits aminopeptidase activity to progressively digest histone tail fragments 1. Beyond histone regulation, JMJD7 functions as a lysyl hydroxylase, catalyzing stereospecific (3S)-hydroxylation at conserved lysine residues (Lys-22 in DRG1 and Lys-21 in DRG2) of translation factors, promoting their RNA interactions 2. JMJD7 operates as a unique homodimer involving N- and C-terminal interactions with disulfide bond formation 2. Functionally, JMJD7 depletion in breast cancer cells significantly decreases proliferation 1, and an oncogenic JMJD7-PLA2G4B fusion transcript promotes head and neck squamous cell carcinoma cell survival through AKT and SKP2 pathway modulation 3. These diverse enzymatic activities position JMJD7 as a potential therapeutic target in cancer 4.