Relationship between asparagine synthetase (AS) mRNA expression induced by pegylated l-asparaginase (PEG-Asp) and clinical response. (A) Baseline AS mRNA expression levels. (B) PEG-Asp–induced changes in AS mRNA expression levels measured after 24 hours of in vivo exposure to PEG-Asp compared with baseline expression levels. Dots represent individual expression values; solid lines, the median expression value per group. For definition of clinical response, see Figure 1.