Protein arginine methyltransferase (PRMT) enzymes play a crucial role in RNA splicing,
DNA damage repair, cell signaling, and differentiation. Arginine methylation is a prominent posttransitional
modification of histones and various non-histone proteins that can either activate or repress
gene expression. The aberrant expression of PRMTs has been linked to multiple abnormalities, notably
cancer. Herein, we review a number of non-histone protein substrates for all nine members of human
PRMTs and how PRMT-mediated non-histone arginine methylation modulates various diseases. Additionally,
we highlight the most recent clinical studies for several PRMT inhibitors.