Yes. Generally, you need to increase the incubation time in the permeabilization buffer (Reagent B). Here are a couple of references:
-Millard I, Degrave E, Philippe M et al. (1998) Detection of intracellular antigens by flow cytometry: comparison of two chemical methods and microwave heating. Clin Chem 44:2320-2330(http://www.ncbi.nlm.nih.gov/pubmed/9799760).
-Parker JE, Mufti GJ, Rasool F et al. (2000) The role of apoptosis, proliferation, and the Bcl-2-related proteins in the myelodysplastic syndromes and acute myeloid leukemia secondary to MDS. Blood 96:3932-3938(http://www.ncbi.nlm.nih.gov/pubmed/11090080).
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