Moreover, the ratio of SKP2 mRNA level in CYH33 treatment group versus that in vehicle group was positively correlated with the T/C values in ESCC PDXs (Fig. 5h), indicating that ESCC PDXs with decreased SKP2 mRNA level upon CYH33 treatment were more sensitive to CYH33 treatment. The gene discussed is SKP2; the disease is esophageal squamous cell carcinoma.