Before revision:  bimodal target distributions can be obtained exploiting a noisy environment even in case of small miRNA-target interaction strength , (ii) an increase in the extrinsic noise shifts the range of target transcription rates that allow bimodality towards higher values, (iii) the protein half-life may buffer bimodal mRNA preventing its distribution from becoming bimodal and that (iv) in a noisy environment different targets may cross-regulate each other's bimodal distribution when competing for a shared pool of miRNAs even if the miRNA regulation is small .
After revision:  bimodal target distributions can be obtained exploiting a noisy environment even in case of small miRNA-target interaction strength . Our results suggest that combining threshold-inducing interactions with extrinsic noise provides a simple and robust mechanism for obtaining bimodal populations not requiring fine tuning. We furthermore characterise the protein distributions dependence on protein half-life may buffer bimodal mRNA preventing its distribution from becoming bimodal and that (iv) in a noisy environment different targets may cross-regulate each other's bimodal distribution when competing for a shared pool of miRNAs even if the miRNA regulation is small .