Importantly, RSK2 is genetically and physiologically linked with human genetic disease known as Coffin–Lowry Syndrome (CLS), but not in RSK1, RSK3, MSK1, and MSK2, indicating that RSK2’s physiological function is not redundant with other RSKs isotypes (20). The gene discussed is RPS6KA1; the disease is Coffin-Lowry syndrome.