Northern blot analysis using (A) sense probe, and (B) antisense probe. (A) Lanes 1 and 2, HL-60 transformed with 3′SS plasmid and pOPRSVI plasmid without insert (mock-transfection); 3, 4, 5, 6, and 7, HL-60 transformed with 3′SS plasmid and pOPRSVI-MARCO plasmid (NF-1); 8, and 9, wild-type HL-60 cells; 1 and 3, without IPTG; 4, with IPTG for 6 hours; 5, IPTG for 24 hours; 6, IPTG for 36 hours; 2 and 7, IPTG for 48 hours; 8, RA for 48 hours; 9, RA for 84 hours. (B) Lanes 1 and 2, mock-transfected HL-60 cells; 3 and 4, HL-60 transformant NF-1 cells; 1 and 3, without, and 2 and 4, with IPTG for 6 hours. In both (A) and (B), bottom panels show a rehybridization of the same blot to a human β-actin probe.