ABSTRACT: CSNK1D, also known as CK1δ, is a crucial gene involved in various biological processes such as cell cycle, transcriptional regulation, apoptosis, cell polarity, and cell motility. It is associated with different cancers and neurodegenerative diseases. This study aimed to investigate the role of CSNK1D in multiple human cancers, particularly hepatocellular carcinoma (HCC), through in vitro experiments. The research utilized various online resources and databases like UCSC, NCBI, GEPIA2, HPA, cBioPortal, SangerBox, UALCAN, and TCGA for analyzing CSNK1D expression, prognosis significance, immune features, and gene alterations in cancers. RT-PCR was employed to evaluate CSNK1D expression in normal liver and liver cancer cell lines. In vitro experiments, including CCK-8, Edu, woun