This gene was identified by involvement in some t(X;14) translocations associated with mature T-cell proliferations. This region has a complex gene structure, with a common promoter and 5' exon spliced to two different sets of 3' exons that encode two different proteins. This gene represents the upstream 13 kDa protein that is a member of the TCL1 family. This protein may be involved in leukemogenesis. [provided by RefSeq, Mar 2009].