Effects of neoadjuvant treatment with letrozole on changes (within 10 to 14 days) in microarray expression of ribosomal proteins. (a) Average changes for the total group, the responding group and the non-responding group. Error bars represent standard errors of the mean. (b) Changes in individual tumours. Red represents an increase in expression and green a decrease. Brightness of colour indicates degree of change, with the brightest colours representing the greatest change. The RPLP0 gene is represented by four probe sets.