MTCP1 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. It represents the upstream 13 kDa protein that is a member of the TCL1 family. MTCP1 may be involved in leukemogenesis. Recombinant human MTCP1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.