Turning on a dimer: New insights into MLL chimeras

In this issue of Cancer Cell, So et al. (2003) demonstrate a novel mechanism for the oncogenic activity of MLL chimeric proteins. By providing coiled-coil or other dimerization domains, the cytoplasmic partners of MLL fusion proteins donate a platform for MLL homodimerization, allowing recruitment of accessory factors needed to activate the critical downstream targets, including selected subsets of the major HOX genes.