Effects of background on MP-score. Plots under different background (α) of MP-score as a function of β (see Materials and Mehods). The value β is defined as the difference between positive and negative interactions divided by the number of total genetic interactions in a complex. Red lines indicate the threshold above which a protein complex is considered to be monochromatic. Under highly biased background (extreme α value), MP-score is not a proper indicator for monochromaticity.