Isoform 1 transcriptionally activates the LYN and BLK promoters and acts synergistically with RUNX1 to transactivate the BLK promoter. Isoform 2 may function in repression of RUNX1-mediated transactivation. Interacts with the LIM domains of LMO2 (By similarity). Interacts via its N-terminal region with RUNX1. Expressed in all fetal and adult tissues examined. Among fetal tissues, highest levels of expression detected in heart, lung, liver and kidney, and lower levels in brain. Among adult tissues, highest levels of expression detected in heart, placenta, lung, skeletal muscle, spleen, thymus, testis and ovary. Moderate expression in prostate, small intestine, kidney, liver and pancreas, and weak expression in colon, brain and peripheral blood lymphocytes. Belongs to the ETS family.