An unusual suspect in cocaine addiction.

Most Mage family members code for antigens on melanoma tumor cells. Maged1 is the black sheep, promiscuously found in normal adult cells, including neurons of the basal ganglia and prefrontal cortex. In this issue of EMBO reports, De Backer et al 1 propose an unexpected role for Maged1. Acute effects of cocaine, such as enhanced locomotion and reinforcement, are gone in mice in which the gene is deleted. In a painstaking combinatorial approach comparing several conditional gene knockout (KO) mouse lines, the authors parse the relevant neural circuits.