Phenylarsine Oxide Inhibits Acid Phosphatase-1

Cells require intracellular communication systems through signal transductions for living. Most signal transductions in mammalian cells are regulated by protein phosphorylation and dephosphorylation, and these reversible reactions can turn on or off biological functions and thus regulate various cellular mechanisms such as growth, proliferation, differ-entiation.1 Protein phosphorylation and dephosphorylation occur on serine, threonine, or tyrosine residues of target proteins by the action of protein kinases and phosphatases. Such phosphorylation and dephosphorylation induce con-formational changes in target molecules and thus regulate their activity. Among phosphorylation-mediated signaling pathways, mitogen-activated protein kinase (MAPK) path-way is the most well-known signaling pathway that com-municates a signal from the outside of cells to the DNA i