sentence: We tested the following reporter lines for the study of epicardium formation in vivo : Tg ( wt1b : GFP ) [ 39 ] , Tg ( − 6.8kbwt1a : GFP ) [ 38 ] and Et ( − 26.5Hsa.WT1-1gata2 : EGFP ) ( hereafter , called Epi : GFP ) [ 35 ] ( Figures 1,2 ) .