Interestingly, hypermethylation of the PSAT1 gene in luminal breast tumors is reminiscent of T cell acute lymphoblastic leukemia (T-ALL), in which hypermethylation of the asparagine synthetase gene sensitizes T-ALL cells to degradation of plasma asparagine with l-asparaginase (Worton et al., 1991). The gene discussed is PSAT1; the disease is T-cell acute lymphoblastic leukemia.