Figure 4. Kinetics of RA-induced ROS generation in HESC.

HESC cells preloaded with DCF-DA as described in Methods were treated with RA (10 μm), TPA (500 nm), TGF-β (5 ng ml⁻¹), or combination treatments as indicated in the figure key. Fluorescence was read immediately after adding the treatments and every minute thereafter up to 2 h. Results showed a significant increase in DCF fluorescence starting approximately 1 h after addition of RA or RA + TGF-β and after 45 min in RA + TPA-treated cultures. No other treatments were significantly different from control cultures. Although readings were taken every minute, results are shown in 20 min intervals for clarity of graphical presentation. Symbols without visible error bars indicate that the s.e.m. was less than the value represented by the width of the symbol. RFU, relative fluorescence units.