RFX2 is a transcription factor that serves as a master regulator of spermatogenesis, particularly controlling gene expression during the haploid phase of sperm development 1. The protein recognizes and binds to X-box regulatory motifs in gene promoters to activate transcription 2. RFX2 knockout mice are viable but exhibit complete male sterility due to arrest in spermatid development prior to elongation, with defects in acrosome formation and complete failure to form flagellar axonemes 1. Through RNA-Seq and ChIP-Seq analyses, RFX2 has been identified as directly controlling 139 genes during spermiogenesis, with particular enrichment for genes required for cilium function and assembly 1. The transcription factor also coordinates cell movement by controlling apical surface expansion in multi-ciliated epithelial cells 3. Beyond reproductive function, RFX2 demonstrates oncogenic potential, acting as a transcriptional suppressor of BNIP3 in non-small cell lung cancer, where its degradation leads to mitophagy activation and drug resistance 4. In spinal ependymoma, RFX2 promotes tumor stemness through epigenetic regulation of PAF1 5. Genetic variants in RFX2 have been associated with male infertility, particularly azoospermia, highlighting its clinical relevance in reproductive health 6.