Update information. To investigate the role of DDX20 in spermatogenesis, we generated Ddx20 flox/flox Ddx4-Cre mice to make a germ cell-specific Ddx20 knockout, and isolated spermatogonia from four-day-old mouse testes by THY1 magnetic beads. We then performed proteomic analysis using protein lysates obtained from THY1 + spermatogonia.