PRKCI and cholangiocarcinoma: In 2017, Qian et al. found that the phosphorylation of serine 59 residue in specificity protein 1 (Sp1) was up-regulated by atypical protein kinase C iota (PRKCI) in CCA through the phosphoproteomic data based on the labeling of isobaric tags for relative and absolute quantitation (iTRAQ) [37].