Fig. 2.

Induction of TH expression by culture in BMP2 plus forskolin in decreased oxygen. A, C, andE are epifluorescence illumination of anti-TH antibody staining of the phase contrast fields shown in B,D, and F, respectively. A,B, A colony grown in decreased oxygen plus 1 ng/ml BMP2 plus 5 μm forskolin. C, D, A colony grown in decreased oxygen without added factors.E, F, A colony grown in 20% oxygen plus BMP2 plus forskolin. No TH expression was seen in cultures grown in 20% oxygen without BMP2 or forskolin in this experiment (data not shown). In general, only rare TH⁺ cells were observed in 20% oxygen cultures. A–F, 10× objective magnification.