– UBASH3A is a member of the T-cell ubiquitin ligand (TULA) family. This family consists of two members. Both of them can negatively regulate T-cell signaling. UBASH3A can facilitate growth factor withdrawal-induced apoptosis in T cells, which may occur via its interaction with AIF, an apoptosis-inducing factor. Alternative splicing of UBASH3A gene results in multiple transcript variants. It interferes with CBL-mediated down-regulation and degradation of receptor-type tyrosine kinases. UBASH3A promotes accumulation of activated target receptors, such as T-cell receptors, EGFR and PDGFRB, on the cell surface. UBASH3A also exhibits negligigle protein tyrosine phosphatase activity at neutral pH. It may act as a dominant-negative regulator of UBASH3B-dependent dephosphorylation. It may also inhibit dynamin-dependent endocytic pathways by functionally sequestering dynamin via its SH3 domain.