GNPDA1 and cancer: The link between GNPDA’s deaminating activity and the ammonium metabolism in cancer cells is still intriguing; a possible route for NH4+ coming from GlcN6P catabolism is its incorporation as the amino group for Glu or Gln by the reverse reaction of glutamate dehydrogenase [85,90,93,94] or by Gln-synthase [95,96].