AKT1 and esophageal squamous cell carcinoma: Based on the different expression of PI3K-Akt pathway-related proteins and HDACs in ESCC cell lines shown in Fig. 1c–e, the efficiency of inhibiting cell proliferation displayed by CUDC-907 was investigated in four different ESCC cell lines (KYSE-150, KYSE-450, KYSE-510, and KYSE-30).