Enhances the phosphorylation and activation of AKT1 and AKT2. Interacts with AKT1 and AKT2 (via PH domain). Does not interact with AKT3. Not found at a significant level in any tissue. Detected in T-cell leukemia bearing a t(X;14) translocation. Plays a key role in T-cell prolymphocytic leukemia. Shares a non-coding 5' exon with isoform 1 which is spliced to a different set of 3' exons encoding an unrelated protein. Belongs to the TCL1 family. MTCP1 and MTCP1NB are transcribed from the same promoter and could be considered the same gene.