In a paper published online in advance in Nucleic Acids Research this week, Jiri Vohradsky from the Czech Republic Academy of Sciences' Institute of Microbiology presents a procedure for the stochastic simulation of gene expression, which he used to investigate the expression dynamics of yeast cyclins and cyclin-dependent kinases. In his simulations, Vohradsky found that the "level of influence of individual regulators in control of the regulated genes is defined," he writes.