Synthetic cel-miR-39, miR-34a-5p mimic, and miR-34a-3p mimic (Applied Biosystem) were serially diluted to final concentrations of 300 nM, 30 nM, 3 nM, 0.3 nM, 0.03 nM, 3 pM, 0.3 pM, 0.03 pM, 3 fM, and 0.3 fM. miR-34a-5p, miR-34a-3p, and cel-miR-39 serial dilutions were reverse-transcribed and assayed using real-time PCR analysis concurrently with RNA extracted from tumor samples and normal tissue. 2.5 μL of exogenous cel-miR-39 at a concentration of 200 amol/μl was introduced as an exogenous normalizer before RNA extraction in all samples. Standard curves for miR-34a-5p and miR-34a-3p and cel-miR-39 were included on each plate of the TaqMan microRNA assays to convert the Ct values of each sample into the corresponding number of microRNA copies. The absolute quantification result of miR-34a-5p and miR-34a-3p was obtained by normalization to cel-miR-39.