The neuroblastoma cell line, SH-SY5Y, can be induced to undergo differentiation in vitro by addition of retinoic acid (RA) (Figure 1C,D) or by the sequential use of RA followed by brain-derived neurotrophic factor (BDNF) (Figure 1E,F) (30,31). The gene discussed is BDNF; the disease is neuroblastoma.