Cellular DBP and E4BP4 proteins are critical for determining the period length of the circadian oscillator

► We focus on the impact of D-box binding transcription factor DBP and E4BP4 on cell autonomous circadian clock. ► Overexpression of DBP and knockdown of E4BP4 lengthen the circadian period length. ► Knockdown of DBP and overexpression of E4BP4 shorten the circadian period length. ► DBP and E4BP4 contribute to maintaining the stable period length of the mammalian cellular circadian clock.