FNBP4 is a 1,017 amino acid protein that contains two WW domains and binds to the Arg/Gly-rich-flanked Pro-rich domains of Formin 1, possibly regulating Formin 1 function. In response to DNA damage, FNBP4 is subject to post-translational phosphorylation, probably by ATM or ATR. The gene encoding FNBP4 maps to human chromosome 11, which houses over 1,400 genes and comprises nearly 4% of the human genome. Jervell and Lange-Nielsen syndrome, Jacobsen syndrome, Niemann-Pick disease, hereditary angioedema and Smith-Lemli-Opitz syndrome are associated with defects in genes that maps to chromosome 11.