<i>PC3/Tis21/BTG2</i> and <i>BTG1</i>, prototype members of the <i>BTG</i>/<i>Tob</i> family, are antiproliferative transcriptional cofactors discovered 35 years ago as genes induced by nerve growth factor and phorbol 12-myristate 13-acetate or associated with lymphocytic leukemia. The gene discussed is BTG1; the disease is lymphoid leukemia.