Human whole blood was fixed, lysed, and permeabilized as per the Cell Signaling Technology Flow Alternate Protocol and stained using Tri-Methyl-Histone H3 (Lys27) (C36B11) Rabbit mAb (Alexa Fluor ® 488 Conjugate). The forward/side-scatter lymphocyte gate was applied to a histogram depicting the mean fluorescence intensity of Tri-Methyl-Histone H3 (Lys27) (C36B11) Rabbit mAb (Alexa Fluor ® 488 Conjugate) (blue) and concentration-matched Rabbit (DA1E) mAb IgG XP ® Isotype Control (Alexa Fluor ® 488 Conjugate) #2975 (red).