Here, we demonstrate that full-length RSK2—which is implicated in several types of cancer, and which is linked to the genetic Coffin-Lowry syndrome—can be overexpressed with high yields in Escherichia coli as a fusion with maltose binding protein (MBP), and can be purified to homogeneity after proteolytic removal of MBP by affinity and size-exclusion chromatography. This evidence concerns the gene RPS6KA3 and Coffin-Lowry syndrome.