Fig. 8. Photomicrographs of neuroblastoma cells (NBP2) in culture after treatment with RO20-1724 and ß-carotene. Control cells (a) four days after plating (50,000 cells/60mm dish), showing mostly round cells; ß-carotene (20 µg/mL)-treated cells (b) four days after treatment showing no significant change in morphology; RO20-1724 (200 µg/mL)-treated cells (c) four days after treatment revealing increased number of cells with neurites; cells treated with RO20-1724 plus ß-carotene (d) for a period of four days showing more differentiated cells than those produced by RO20-1724 treatment alone; cells treated with RO20-1724 plus ß-carotene for a period of eight days (e) and (f) 11 days [55].