Fig. 4. Single-cell GAL1–GFP expression in response to varying glucose levels in cells carrying the entire GAL1 regulatory network. Cells carrying the integrated GAL1–GFP reporter (YSB31) were grown in 2% glucose media, washed, and transferred to media containing the indicated concentrations of glucose and 2% galactose for 14 h. Cells were harvested at mid-log phase and then analyzed for GFP expression by FACS.