Figure 2: Effect of RA on cell growth. Cells were treated at concentrations ranging from 10 μg/ml to 80 μg/ml of RA for 24 hrs. and then treated with WST- 1 for 3 h. UM-SCC-6 (A) and UM-SCC-10B (B) cell viability was determined by measuring absorbance at 460 nm. Data are expressed mean ± SD (n = 5). (C) UM-SCC-6 cells were treated with 80 ug/ml RA and expression of P-ERK was measured by western-blotting. **p<0.01, ****p<0.0001 vs control.