HAAO and neoplasm: On the other hand, the expression of the KYNU, HAAO, ACSMD, and QPRT enzymes, that constitute the ‘long branch’ of the KP and drives to NAD+ synthesis, were increased in the LLG IDHw and GBM compared to the brain cortex, which could promote the production of toxic molecules for anti-tumor immune populations [26,27] and support the correlation of the KP enzymes with tumor malignancy.