Therefore, we speculated that preferential localisation of circPSD3 in the cytoplasm may retain HDAC1 in the cytoplasm, thereby reducing the inhibitory effect of HDAC1 on the transcription of SERPINB2. Consistent with this hypothesis, immunofluorescence and nuclear and cytoplasmic fractionation assays showed that circPSD3 knockdown significantly reduced the protein levels of HDAC1 in the cytoplasm of HCC cells (Fig. 6M, N). Here, HDAC1 is linked to hepatocellular carcinoma.