Modeling the distribution of spacing distances between matches to the CDK consensus. Fit of one (black trace) or two multivariate geometric components (blue and red traces) to the observed spacings (thin black trace) in the 'known' targets. The 'known' targets exhibit an excess of short spacings over what would be expected under the single geometric. The inset shows the geometric fit (black trace) to the spacings observed (thin black trace) in the 'unbiased negatives' and shows much better agreement. See text for details. CDK, cyclin-dependent kinase.