Human embryonic stem cells (HUES4) were differentiated as monolayer cultures on matrigel coated dishes using a protocol described in Kroon et al, Nat Biotechnol. (2008). Inhibin beta A ( ab50051 ) and Wnt3a (ab81484) were added to cultures to direct differentiation towards definitive endoderm. This image was taken 3 days after induction, where the definitive endoderm marker FOXA2 ( ab40874 in green) is abundant. Dapi staining is shown in blue. Magnification: 200x. Negative controls of fluorescently conjugated secondary antibodies only showed no staining.