In the CIS we observe a higher expression of hexokinase 1 (HK1) with consequent high levels of glucose-6-phosphate (GLU6P) derived from glucose, with an activation of the pentose phosphate pathway (PPP) (represented by G6PD and PGD genes) and serine pathway (PSAT1 gene) but without an activation of glycolysis (GPI, LDHA genes). This evidence concerns the gene G6PD and in situ carcinoma.