SELENOP and male infertility: In particular, it has been reported that ApoER2 gene-deficient mice show phenotypes (neurological disorders and male infertility) similar to those of SeP-deficient mice [23,24], it would be important to understand not only SeP but also the ApoER2 (as the SeP/ApoER2 axis) to understand Se transport and its metabolism; however, details remains unknown.