Stochasticity and Cell Fate Stochastic mechanisms can diversify cell fates in nervous systems. In the Drosophila retina, the stochastic distribution of color-sensing photoreceptors is controlled by the random, On/Off expression of the Spineless transcriptional regulator. Johnston and Desplan (p. 661 ) found that each allele of spineless makes an intrinsically random expression choice controlled by an enhancer and two silencer DNA elements acting at long range. spineless alleles communicate between chromosomes using activating and repressing mechanisms to determine the frequency of expression and coordinate expression state. These findings suggest critical roles for intrinsically random expression decisions and interchromosomal communication in stochastic cell fate specification.