The leucine-rich diet prevented the decrease in plasma insulin level associated with tumour growth in the WL group (L = 6.216 ± 0.872 ng.mL-1; WL = 3.547 ± 0.286*; PL = 5.019 ± 0.552; *p < 0.05 compared to C and P). The gene discussed is INS; the disease is neoplasm.