STAT1 and neoplasm: In summary (Fig. 6), our study showed that when treating tumor cells with the HDAC6 inhibitors (ACY-1215), on the one hand, ACY-1215 increased the acetylation level of STAT1 and inhibited the phosphorylation of STAT1, preventing STAT1 from entering the nucleus to play a transcriptional regulatory role in PD-L1.