In this study, we used Drosophila testis as a model system to test the functional relevance of a NOA-associated human gene, FOXN3. Although loss of CHES-1-like, the fly ortholog of FOXN3, did not result in spermatogenesis defects, the ectopic expression of CHES-1-like in germ cells blocked spermatocyte differentiation and induced tumor-like structure formation. Here, FOXN3 is linked to neoplasm.