Fig. (1) Cell growth of Ca9-22 cells. RA-treated (red line) and untreated (blue line) Ca9-22 cells. Ca9-22 cells were treated with 10-6M of 9-cis RA. Ordinate: cell number; abscissa: days after cells were seeded, with or without 9-cis RA. The experiments were repeated twice, and a representative result is shown.