Trapped ES clone Accession L1 integrated site Gene Gene product A2 NM_025914.2 Chr.10qC1: 89189558 Actr6 ARP6 actin-related protein B9 NM_008092.3 Chr.14qD1:63819210 GATA4 GATA binding protein 4 A8 NM_025863.3 Chr.3qE1: 68838551 TRIM59 Tripartite motif containing 59* B1 NM_023764.3 Chr.7qF5: 149067490 Tollip Toll-interacting protein *contained three L1 integration sites

Table 1: Genes identified by L1 insertional mutagenesis that displayed defect in ES cell differentiation.