FIGURE 6.

Exogenous expression of PER under the control of the Per2 promoter enhances robustness of circadian rhythms in wild-type MEFs. A and B, robustness of bioluminescence rhythms is enhanced in PER2 (A) or PER1 (B) MEFs compared with GFP MEFs. Exogenous PER1-V5 was overexpressed relative to endogenous PER1 in GFP MEFs as shown in the right panel of B. More traces from separate experiments are shown in supplemental Fig. S5. Adv, adenovirus. C, quantification of A and B. Periods were calculated using the first four peaks, and amplitudes were calculated using five peaks after the fourth peak. For GFP, n = 12; for Per2-PER2 (P2-P2), n = 12; and for Per2-PER1 (P2-P1), n = 6. *, p < 0.05; ***, p < 0.001.