Former venture capitalist Ellen Pao could take the stand as early as Thursday in her gender discrimination lawsuit against her previous employer Kleiner Perkins Caufield & Byers, giving testimony that will likely make or break the case. Questioning Pao provides the best opportunity for each side to clinch their arguments, but it is also extremely risky, according to employment law attorneys following the trial. The lawsuit, which the former Kleiner Perkins partner filed in 2012 against the venture capital firm, has helped spark a broad and ongoing discussion about sexism in Silicon Valley.