PIN1 and hepatocellular carcinoma: For instance, small-molecule API-1 interacts with Pin1 Lys63 and Arg69 via non-covalent hydrogen bond or π interaction, suppressing HCC via enhancing the expression of mature miRNAs.4 Peptidyl non-covalent inhibitors are developed to mimic Pin1 substrate and often have a high Pin1 affinity.