MM-derived autocrine and exogenous SHH induce MM-cell drug resistance. Percentages of apoptotic (A) ARP-1 or (B) CAG cells induced by BTZ (10 nM), dexamethasone (Dex; 10 μM), or Mel (5 μM) in the presence or absence of aSHH or control IgG (5 μg/mL). Also shown are percentages of apoptotic ^vecARP-1/CAG, ^SHH+ARP-1/CAG, and ^SHH–ARP-1/CAG cells induced by different doses of (C,D) BTZ (0 to ∼50 nM) or (E,F) Mel (0 to ∼10 μM). Apoptosis assay was performed for a 24-hour culture by using Annexin-V staining. *P < .05; **P < .01.