In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Q: MATERIALS AND METHODS : The cells were stimulated by 100 ng / mL TPO and / or 100 ng / mL TGF - beta1 and analyzed for proliferation ( 3H thymidine incorporation ) , viability ( trypan blue exclusion ) , and protein expression and phosphorylation ( Western blot ) .
A:
TGF - beta1