Key players in the Notch pathway are the TLE genes, which are human homologs of the Drosophila Groucho gene. Groucho is a transcriptional repressor that plays a key role in neurogenesis, segmentation and sex determination.Transducin-like enhancer protein 1 (TLE1) is a protein that is encoded by the TLE1 gene and is involved in control of hematopoiesis, neuronal, and terminal epithelial differentiation. Positive immunohistochemical nuclear staining with anti-TLE-1 has been shown to be a useful addition to an IHC panel when differentiating synovial sarcoma from other soft tissue malignancies.