May be required for cellular fusion during osteoclastogenesis. Ubiquitous. Highest level of expression in kidney. Present in monocytes, osteoclasts, macrophages, synoviocytes and synovial lining cells (at protein level). A chromosomal aberration involving TCTA is associated with T-cell acute lymphoblastic leukemia (T-ALL). Translocation t(1;3)(p34;p21). Belongs to the TCTA family.