Table 1. Frequency of 3′ UTR reporter repression for artificial miRNAs with and without seed matches in the reporter.

Reporter	Artificial miRNA seed match in reporter			No artificial miRNA seed match in reporter			P value, Fisher's test
	Reporter repressed	Reporter not repressed	% Reporter repressed	Reporter repressed	Reporter not repressed	% Reporter repressed
PC	78	151	34.1%	10	69	12.7%	0.00026
GLS	58	142	29.0%	18	90	16.7%	0.01849
GAPDH	7	27	20.6%	20	254	7.3%	0.01870
EMPTY				8	300	2.6%

For each 3′ UTR reporter indicated, the artificial miRNAs were classified by whether they had a seed match in the reporter and whether the reporter luciferase activity was significantly repressed by the miRNA (activity > 2 SD below the reporter alone mean and q < 0.05). The significance of the association between seed matches and reporter repression for each 3′ UTR reporter was calculated using Fisher's exact test.