FGD4（FYVE， RhoGEF and PH domain containing 4），癌症关联基因，基因ID：121512，该基因编码一种蛋白质，参与肌动蛋白细胞骨架和细胞形状的调节该蛋白含有一个肌动蛋白丝结合结构域，该结构域与其dbl同源结构域和一个pleckstrin同源结构域一起可以形成小孢子。该蛋白能独立于肌动蛋白丝结合区激活MAPK8，并通过结合的GDP与游离GTP的交换参与CDC42的激活CDC42的激活也使该蛋白在介导微小隐孢子虫（一种感染胃肠道的细胞内寄生虫）的细胞侵袭中发挥作用该基因突变可导致4h型腓骨肌萎缩症（cmt4h），一种外周神经系统疾病。已经发现该基因的多个交替剪接的转录变体编码不同的亚型。[由RefSeq提供，2015年1月]This gene encodes a protein that is involved in the regulation of the actin cytoskeleton and cell shape. This protein contains an actin filament-binding domain， which together with its Dbl homology domain and one of its pleckstrin homology domains， can form microspikes. This protein can activate MAPK8 independently of the actin filament-binding domain， and it is also involved in the activation of CDC42 via the exchange of bound GDP for free GTP. The activation of CDC42 also enables this protein to play a role in mediating the cellular invasion of Cryptosporidium parvum， an intracellular parasite that infect。