Plasmids, antibodies, and chemicals

Maspin-3′UTR was constructed in to pMIR-REPORT™ Luciferase plasmid (Ambion, Austin, TX, USA) [28]. Mutations of indicated sites in maspin-3′UTR and Flag-IKKα were generated using a Quickchange site-directed mutagenesis kit (Stratagene, La Jolla, CA, USA) according to the manufacturer's instructions. All of the above plasmids were confirmed by DNA sequencing. We purchased antibodies against IKKα, phospho-IKKα Thr23, IKKβ, and maspin from Santa Cruz (Santa Cruz, CA, USA), antibody against Flag-tag from Sigma-Aldrich (St. Louis, MO, USA), and antibody against phospho-IKKα Thr-23 (for IHC) from Abnova, The validated miRNA inhibitors were purchased from Dharmacon (Lafayette, CO, USA). The validated shRNA for negative control and IKKα were purchased from National RNAi Core Facility at Academia Sinica (Taipei, Taiwan). Tripure isolation reagent for RNA isolation was purchased from Roche (Indianapolis, IN, USA). The MMLV First-Strand cDNA Synthesis kit and Universal probelibrary Probe#21 was purchased from Roche (Indianapolis, IN, USA). The KAPA SYBR^® FAST Master Mix (2X) and KAPA Probe FAST Universal qPCR Kit were purchased from Kapa biosystem (Woburn, MA). The chemotherapeutic drugs, doxorubicin hydrochloride was purchased from Sigma-Aldrich (St. Louis, MO, USA). Luciferase assay system was purchased from Promega (Madison, WI, USA). Actinomycin D was purchased from Sigma-Aldrich (St. Louis, MO).