Help --GFP

[jia]

Reccently I got a Tie-2- GFP ES cell line and I should differentiat these ES cells into blood vessels and then check them under the confocal miroscope. But the problem is that I can not see any of the green gluorescence in several days of differentiation when the blood vessel morphology have been shown after stained with CD31 antibody . The tie-2 is expressed on the endothelial cells during angiogenersis . So I do not know what's the problem is . By the way the ES cells given by the other lab have been sucessfully used in the differentiation of the blood vessels . So could anyone tell me what happened to my cells, what I gona do

[jia]

do any one could tell me how many possibilites there are for not generating furorescent by the GFP