AML1/ETO siRNAs support differentiation response to RA of human t(8;21)-positive cells (SKNO-1). SKNO-1 cells were infected (si-A/E) or not (mock) with a lentiviral vector containing a construct expressing siRNAs against the region of fusion of the AML1/ETO mRNA (siA/E-RNA). (A) Expression levels of siRNAs as evaluated by Northern blot analysis on total RNA (5 μg) from mock and si-A/E samples. U2 snRNA was used as a loading control. (B) AML1/ETO mRNA amounts were normalized using c-abl mRNA quantity values and quantified in mock and si-A/E cells by qRT-PCR. The results represent the average of 3 independent evaluations ± SE. (C) Western blot analysis was performed on total cell lysates (50 μg) from mock and si-A/E cells using an anti-AML1 antibody. The immunodetection of the anti–β-tubulin antibody was used as loading control. (D) RARβ2 mRNA expression from mock and si-A/E–infected cells treated or not with RA (1 μM) for 48 hours was measured by qRT-PCR. The results represent the average of 3 independent evaluations ± SE. (E) Effect of 72-hour treatment with RA (1 μM) on the percentage of cells positively stained for CD11b and CD14 surface markers as measured by FACS analysis in mock and si-A/E cells. The results represent the average of 3 independent evaluations ± SE.