PMA-stimulated NADPH oxidase activity by CHO 91/47/67 cells expressing p22phox point mutations. CHO 91/47/67 cells expressing either no p22phox (Mock), wild type p22phox (wtp22), Pro-156 to Gln p22phox (P156Q), Thr-132 to Ala p22phox (T132A), or Thr-147 to Ala p22phox (T147A) were stimulated at 2 × 106 cells/ml in the presence of 100 μl of Diogenes with either buffer (open bars) or 100 nm PMA (filled bars) for 1–2 h. Data represent four separate transfections and are expressed as mean ± S.E. (error bars) of the RLU/min measured from each p22phox condition. NS, not significant; *, p < 0.05. Western blot analysis for expression of p22phox and p47phox was performed as described under “Experimental Procedures,” and the results from a representative experiment are shown.