RARA and acute promyelocytic leukemia: Another study indicated that a DNA vaccine containing the PML-RARα segment and tetanus fragment C (FrC) sequences could increase survival times when used alone or in combination with all-trans retinoic acid (ATRA) in a mouse APL model [37], which is similar to a study that demonstrated that DNA vaccination with ATRA confers the effective boosting of interferon-gamma-producing and cytotoxic T-cells in leukemic mice [39].