Plays a role in T-cell signaling pathway. Isoform 2 may play a role in T-helper 2 (Th2) signaling pathway and seems to represent the first proximal signaling protein that links T-cell receptor-mediated signal to the activation of c-Maf Th2 specific factor. Interacts with FLNA. Isoform 2 is translocated to the nucleus and is specifically recruited during minimal change nephrotic syndrome (MCNS) (PubMed:12939343) (PubMed:15616553). Detected in nuclear and cytoplasmic compartments during MCNS relapse (PubMed:12939343) (PubMed:15616553). Expressed in cytoplasm only during MCNS remission and absent in normal patients (PubMed:12939343). Isoform 1 is expressed in peripheral blood mononuclear cells and kidney. Lower expression in brain and liver. Expression is down-regulated in activated cells. Isoform 2 is expressed in lymphocyte precursors, however, expression shuts down during maturation and differentiation in thymus and fetal liver. Expressed in fetal liver.