Characteristics of RPP microarrays and validation of β-actin as protein for normalization. (A) Mean fluorescence intensity (MFI) of SLP-76–specific signal detected in spots containing equal protein amount of PBMC or intestinal Caco-2 cell lysates. Alternatively, exogenous RNase-2 was added to PBMC lysate and specific RNase-2 signals were normalized to β-actin content (bar graphs). Immunodetection of Western blots (WB) with specific antibodies for SLP-76 and RNAse-2 in the corresponding lysates are shown in right panels (300 000 cells/lane). (B) Quantitative analysis of Lck detection in serially diluted PBMC lysates using specific antibodies. The bottom panel shows corresponding spots printed in triplicate. (C) β-Actin as protein for normalization. β-Actin and β2-microglobulin contents were measured in lysates of sorted N, CM, EM, and E cells following SDS-PAGE and immunoblotting with specific antibodies. Shown are representative immunodetection and quantitative measurements of β-actin signals from WB in 3 cumulated subjects.