Ab226943

The fusion proteins were stained with anti-human CD9 antibody (produced in mouse, 60232-1-lg, Proteintech, Rosemont, IL, USA), or anti-human AGO2 antibody (produced in rabbit, ab226943, Abcam, Boston, MA, USA).
The membrane was incubated with 1:1000 diluted primary antibody overnight at 4 °C and then with 1:500 diluted horseradish peroxidase conjugated goat anti-mouse secondary antibody (7076, Cell Signaling Technology, Danvers, MA, USA) and goat anti-rabbit secondary antibody (7074, Cell Signaling Technology) for 2 h at room temperature. Antibody dilutions were made in Immobilon^® Block—CH solution (Chemiluminescent Blocker, Merck Millipore, Darmstadt, Germany). After each incubation step, membranes were washed three times in the PBS containing 0.2% Tween-20 for 5 min. Protein bands were detected using SuperSignal™ West Pico PLUS Chemiluminescent Substrate (Thermo Fisher Scientific™) with ChemiDoc XRS System (Bio-Rad Laboratories).

The paraffin-embedded BM core biopsies obtained from patients with MM at NDMM (n = 3), at complete response (CR, n = 3), at diagnosis of RRMM (n = 3) and a non-cancerous BM (n = 1) were analyzed for the protein expression of MTA2 and AGO2. IHC staining was performed on a Ventana Discovery XT automated system (Ventana Medical System, Tucson, AZ, USA), using the primary antibody raised against MTA2 (diluted 1:500; ab8106, Abcam, UK) and AGO2 (diluted 1:200; ab226943, Abcam, UK), as described in the Supplementary Methods in S1 File. Two slides from each biopsy were stained with hematoxylin and eosin (H&E) for routine histological evaluation.