siRNA knockdown of the overlapping kinase targets of the circadian period–altering compounds identified here led to long period length in circadian oscillations (mostly double hits, i.e., hit by two independent siRNA pairs). Data obtained from BioGPS circadian layout (http://biogps.gnf.org/circadian/) (Zhang et al, 2009). CRY2 siRNA was used as a positive control and GL2 siRNA was used as a negative control. (A) Luminescence profiles for independent siRNA pairs against the target kinases. (B) Period length obtained by the curve fitting. Data from each experiment is represented by a dot, and mean period length is shown as a horizontal bar. *** indicates P < 0.0001, ** indicates 0.0001 < P < 0.001, and * indicates 0.001 < P < 0.05 (t test).