LCT and neoplasm: The reduction in HP Lac/Pyr in Ldha-knockdown mice correlated with an approximate 80% reduction in Ldha expression and LDH activity, but no changes in the monocarboxylate transporters (Mct1 and Mct4), nor in HP 13C urea perfusion or expression of factors impacted by the hypoxic tumor microenvironment (Hifα and Vegf), thus demonstrating the specificity of Ldha-knockdown.