PCK2 and lung adenocarcinoma: Interestingly, the mitochondrial enzyme phosphoenolpyruvate carboxykinase (PCK2), which sustains gluconeogenesis, has been found to be more frequently upregulated in lung adenocarcinomas than in epidermoid tumors [58], and PCK2 expression is associated with a better prognosis compared to the expression of glycolytic expression of GLUT1 [58].