E-Mail IMAGE: Reversible modulation of the circadian clock using chronophotopharmacology. Using light to interconvert two isomers of a photo-responsive small molecule, it is possible to pace cellular time. While irradiation with violet... view more Credit: Issey Takahashi The biological clock is present in almost all cells of an organism. As more and more evidence emerges that clocks in certain organs could be out of sync, there is a need to investigate and reset these clocks locally. Scientists from the Netherlands and Japan introduced a light-controlled on/off switch to a kinase inhibitor, which affects clock function. This gives them control of the biological clock in cultured cells and explanted tissue. They published their results on 26 May in