Moreover, on the basis of gene expression analysis and intracellular protein levels (Figure 2B and 2C), the different cancer cells could be divided into two groups displaying low (U87, HeLa, MDA-MB and MCF7: Group I) or high (A375, A375M, HepG2 and Caco2: Group II) protein, activity and transcript levels of APEH and proteasome (β-5 subunit). The gene discussed is APEH; the disease is cancer.