A small molecule inhibitor of Rac1/Cdc42 GTPases, which are upstream of IQGAP1, was reported to suppress growth of primary human prostate cancer xenografts46 and a 40 amino acid ERK1/2-binding IQGAP1 WW domain peptide that disrupted IQGAP1-ERK1/2 interactions was shown to inhibit RAS- and RAF-driven tumorigenesis47. Here, MAPK3 is linked to prostate cancer.