Background: The Split ends (Spen) family are large proteins characterised by N-terminal RNA recognition motifs (RRMs) and a conserved SPOC (Spen paralog and ortholog C-terminal) domain. The aim of this study is to characterize the family at the sequence level. Results: We describe undetected members of the Spen family in other lineages (Plasmodium and Plants) and localise SPOC in a new domain context, in a family that is common to all eukaryotes using profile-based sequence searches and structural prediction methods. Conclusions: The widely distributed DIO (Death inducer-obliterator) family is related to cancer and apoptosis and offers new clues about SPOC domain functionality. Background The aim of this study was to characterize the Spen family at the sequence level. The Spen family of proteins participates in various biological processes. It is involved in neuronal cell fate, survival and axonal guidance [1-3], cell cycle regulation [4], and repression of head identity in the embryo...