When HCC patient tissues were cultured on the oxygen gradient chip for 4 days (Fig. 3b, Supplementary Fig. 6), typical HCC showed increased expression of protein markers associated with hypoxia-mediated stemness (CAIX), cancer invasiveness (K19), and microvascular invasion (CD34) on the normoxic side compared to the hypoxic side. Here, CA9 is linked to hepatocellular carcinoma.