Table 2.

2×2 contingency table was set to determine whether a pair of motifs occurred more often together than would be expected by chance where: q is the count of proteins with motifs a and b; m is the count of proteins with motif a; n is the count of proteins with motif b; N is the count of all identified phosphorylated proteins. Enrichment Factor (EF) calculated as EF_a,b = q/(mn/N).

	Observed count	Expected count
Proteins with motif a and b	q	mn/N
Proteins without motif a and b	N – m – n + q	((N − m)(N − n))/N