JanA and janB regulate somatic sex differentiation. Somatic and germline cells. Isoform B is expressed in both sexes and in somatic and germ line cells. Isoform A is expressed in males and is germ line specific. The non-sex-specific transcript is present at all stages. Transcription of janA gives rise to two sex-specific and one non-sex-specific transcripts. Belongs to the janus family.