abrupt (ab) encodes a transcription factor that negatively regulates ecdysone signaling, as it binds to the product of tai. It regulates animal survival, organogenesis and multiple tissue morphogenesis, epithelial cell fate, cellular sexual identity, neuron differentiation and neuronal identity switch, cell migration, oncogenesis and germline differentiation. In many cell types, the product of ab is post-transcriptionally repressed by the steroid-induced miRNA
let-7.