TASP1 encodes a conserved threonine protease that activates histone methyltransferases critical for transcriptional control. The enzyme cleaves and activates KMT2A/MLL1 and KMT2D/MLL2, thereby regulating expression of homeobox genes and key cell-cycle regulators including CCNA1, CCNB1, CCNE1, and CDKN2A. Beyond its canonical substrates, TASP1 also proteolytically processes the basal transcription factor TFIIAα-β and the actin motor protein Myo1f to fine-tune filopodia dynamics and regulate hematopoietic stem cell fate during embryonic development 12. Loss-of-function variants in TASP1 cause Suleiman-El-Hattab syndrome, a histone modification disorder characterized by developmental delay, microcephaly, distinctive facial features, and multiple congenital anomalies affecting the heart, skeleton, and posterior fossa 34. The phenotypic overlap with Kabuki and Wiedemann-Steiner syndromes reflects TASP1's essential role in the histone methylation pathway 1. In cancer, TASP1 is upregulated in hepatocellular carcinoma, gastric cancer, and gallbladder cancer, where it promotes proliferation and migration via the PI3K/AKT and EMT signaling axes 567. These findings identify TASP1 as a potential therapeutic target in solid malignancies, though specific inhibitors have not yet been named in clinical development.