HDAC6 and cholangiocarcinoma: The mechanisms underlying the loss of cilia in CCA include the increased activity of deacetylases like HDAC6 and SIRT1, which removes the acetyl group from the α-tubulin in the ciliary axoneme in cholangiocytes and leads to cell proliferation, migration, and invasion in CCA (Gradilone et al., 2013; Pant et al., 2020, 2021).