EP4 Receptor Expression in HT-29 Cells and in Human CRC. (1a). Representative amplification plot for the various EP receptors in HT-29 cells. The no template control (NTC) is indicated by the grey line. (1b) The number of cycles required to achieve exponential amplification of identical template from a panel of 8 colorectal tumours by qRT-PCR. The chart shows mean values +/- SEM for n = 8. Repeated measures ANOVA (overall) p = 0.0002, significant p values are shown and represent Bonferroni multiple comparisons test between selected groups.