Drosophila regulatory factor X is an embryonic type I sensory neuron marker also expressed in spermatids and in the brain of Drosophila.

We report the expression pattern of a Drosophila transcription factor, Drosophila regulatory factor X (dRFX), which belongs to the RFX winged-helix transcription factor family. dRFX is distributed in type I sensory neuron lineage of the peripheral nervous system throughout Drosophila development and thus represents the first described type I lineage characteristic marker in Drosophila. In addition, dRFX is also detected in the brain throughout development and in spermatids in adult flies.