MNS1 and seminoma: MNS1 (meiosis-specific nuclear structural 1) encodes a coiled-coil protein of unknown function, which is essential for spermiogenesis.42RBMXL2 (also called hnRNP G-T) codes for an hnRNP expressed almost exclusively in testes and GCTs believed to function during meiotic prophase or to act as a germ cell-specific splicing regulator.43 Hence, the silencing of these genes in non-seminomas may also play a role in their differentiation towards somatic cell lineages.