Fig. 6.

RA suppression of KOR expression requires protein synthesis. A, RT-PCR was conducted to determine KOR isoform expression in P19 control (ctrl), treated with RA for 3 (RAD3), 5 (RAD5), and 7 (RAD7) d, and treated with RA in the presence of cycloheximide at the final day of culture (RA+CH). Statistical analyses of KOR isoform expression are shown at the left panelbelow the picture. B, Parallel experiments examining the effect of cycloheximide on KOR expression. P19 was treated with RA (RAD3), RA plus cycloheximide (RAD3+CH), or cycloheximide alone (CH). Statistical analyses are shownbelow the picture.