PIN4 is a member of the parvulin subfamily of the peptidyl-prolyl cis/trans isomerase protein family. The encoded protein catalyzes the isomerization of peptidylprolyl bonds, and may play a role in the cell cycle, chromatin remodeling, and/or ribosome biogenesis. PIN4 may play an additional role in the mitochondria [taken from NCBI Entrez Gene (Gene ID: 5303)].