PROS1 and Globozoospermia: It has been reported that the inactivation of Asn-Pro-Phe (NPF) motif-containing protein Hrb also causes the globozoospermia-like phenotype in a mouse model.9 In Hrb-deficient germ cells, the interaction between the transport vesicle adaptor protein Eps15 and the AP1 complex is disrupted, thus indicating that the AP1 complex has a critical role in the docking and/or fusion of Golgi-derived pro-acrosomic vesicles.