Before revision:  We present a quantitative analysis of the network properties of three key biological systems for which sufficiently comprehensive datasets are now available: transcription factors, microRNAs  and protein kinases . We find that some parameters defining general network properties vary only within limited ranges , suggesting the existence of common control strategies in biology.
After revision:  We present a quantitative analysis of the network properties of three key biological systems for which sufficiently comprehensive datasets are now available: transcription factors, microRNAs and protein kinases ) and a drug-target network. Certain network properties seem universal across systems and species , suggesting the existence of common control strategies in biology.