In contrast, transfection of shRNAs targeting Smad4 (sh-Smad4) into SH-SY5Y and SK-N-SH cells resulted in decreased protein and transcript levels of Smad4 and increased HPSE expression in NB cells, when compared to those stably transfected with scramble short hairpin RNA (sh-Scb) (Fig. 1e,f). The gene discussed is SMAD4; the disease is neuroblastoma.