Acute myeloid leukemia (AML) is an aggressive cancer of white blood cells with few effective targeted therapies available to treat it. Cold Spring Harbor Laboratory (CSHL) Professor Christopher Vakoc (photo), MD, PhD, and former graduate student Sofya Polyanskaya, PhD, found that AML cells rely on a previously little-known protein called SCP4 for survival. Their discovery points to a potential new therapeutic approach for this disease. SCP4 is a phosphatase, a type of protein that regulates cell activity by removing phosphates from other proteins. Another type of protein called a kinase puts those phosphates back on. The number of phosphates added to or subtracted from a protein—its phosphorylation level—determines its activity. Polyanskaya discovered that SCP4 could pair with either one of two similar kinases called STK35 and PDIK1L. AML cells appear to need the phosphatase and kinases to work together to survive; turning off the gene that produces SCP4 kills the cancer cells.