GOPC and Globozoospermia: Pcsk4-null sperm exhibit low expression of ACRBP.34 ATG7 regulates GOPC during acrosome biogenesis.29 The levels of ZPBP1 and SPACA1 are extermely low in the Gopc−/− mouse testes.28 PICK1 interacts and cooperates with GOPC and CK2α' in acrosome biogenesis.19 Recently, He et al.43 identified ICA1L as a new BAR domain-binding partner of PICK1, and sperm from Ica1l−/− mice exhibit the characteristics of globozoospermia.