The proteins termed TLE in humans, Grg in mice and Groucho in Drosophila 
constitute a family of transcriptional corepressors. In mammalians there are 
five different genes encoding an even larger number of proteins. Interactions 
between these TLE/Grg proteins and an array of transcription factors has been 
described. But is there any specificity? This review tries to make a case for a 
non-redundant function of individual TLE/Grg proteins. The specificity may be 
brought about by a tightly controlled temporo-spatial expression pattern, 
post-translational modifications, and subtle structural differences leading to 
distinct preferences for interacting transcription factors. A confirmation of 
this concept will ultimately need to come from genetic experiments.