In this study, it was demonstrated that the genetic knockdown of Ldha in prostate tumors could be monitored via the rate of conversion of HP 13C-pyruvate to 13C-lactate, with a significant reduction in HP Lac/Pyr in Ldha-knockdown mice versus a significant increase in control mice occurring by the 1-week timepoint. The gene discussed is LDHA; the disease is prostate neoplasm.