Figure 4.

The cross correlation function reveals regulatory connections. (A) A stochastic mathematical model of noisy LacI co-regulation (Methods) predicts a large, symmetric yfp-rfp cross correlation function and smaller asymmetric rfp-cfp and yfp-cfp cross correlations. (B) Experimental cross correlation between yfp and rfp averaged over 5 microcolony movies. The error bars show the standard error between movies. (C) Experimental cross correlation between rfp and cfp. (D) Experimental cross correlation between yfp and cfp.