Table 1.

Overview of Selected Features from the Commercially Available shRNA Expression Libraries from the Hannon and Elledge Lab (H&E), the RNAi Consortium (TRC) and the Netherlands Cancer Institute (NKI). State of January 2010

	H&E library	TRC library	NKI library
Distributor	Open Biosystems, Thermo Scientific	Open Biosystems, Sigma-Aldrich	Geneservice
Retroviral vector	pSM2	none	pRS
Lentiviral vector	pGIPZ	pLKO1	none
Number of covered genes	18,000	15,000	8,000
Avgerage constructs per gene	2.5 (pGIPZ) 2.8 (pSM2)	5	3
Total constructs	45,000 (pGIPZ) 50,000 (pSM2)	80,000	24,000
shRNA sequence	22 nt stem, 19 nt loop	21 nt stem, 6 nt loop	19 nt stem, 9 nt loop
Molecular tag	half hairpin, external 60 nt barcode	half hairpin	full-length hairpin