Discusses research being done on the regulation of mitochondrial outer membrane permeabilization and apoptosis by destabilization of MCL-1 by glycogen synthase kinase-3. Reference to a study by U. Maurer et al., published in the 2006 issue of "Molecular Cell Biology"; Function of glycogen synthase kinase-3 in hematopoietic cells; Results of the expression of an MCL-1 phosphorylation-site mutant in Interleukin-3-dependent cells.