Despite being first described several years ago, the roles of the Schlafen (SLFN) family of proteins remain largely unknown. The SLFN genes are preferentially expressed in lymphoid tissues and differentially regulated during thymocyte maturation. It is thought that many play roles in cell growth, hemopoietic cell differentiation, and T cell development and maturation. Most members contain at least one divergent AAA domain (AAA_4) that may play a role in ATP binding. SLFN14 is a recently identified member of the SLFN family; its role has yet to be determined.