CCNYL1 and male infertility: Furthermore, cyclin Y-like 1 (Ccnyl1) KO mice, which develop normally but exhibit male infertility associated with asthenozoospermia (reduced sperm motility) also supports this hypothesis, as Ccnyl1 KO led to a substantial reduction in Cdk16 expression in the testis, suggesting its involvement in regulating Cdk16 protein stability.