Expression of integrins in α₄-R/A^GFFKR mice. (A) Cell-surface expression of integrins on splenic lymphocytes from wild-type (WT) and α₄-R/A^GFFKR (KI) mice. Numbers denote mean fluorescent intensity (MFI). Background binding of isotype control antibodies is shown with open histograms. (B) Cell-surface and total (cell surface plus intracellular) α₄ protein expression in WT and KI splenocytes. Expression of α₄ integrins was measured by immunofluorescent cytometry in the absence (for cell-surface expression) or presence (for total expression) of permeabilization treatment. Ratios of MFI values are shown. (C) α₄ mRNA expression in spleen (SP) and peripheral lymph node (PLN) cells. (D) mRNA expression of GRP78 and the spliced form of XBP-1, markers to probe levels of UPR in WT and KI splenocytes. (C,D) mRNA expression was measured by a quantitative RT-PCR and normalized by GAPDH mRNA levels. (B-D) Data represent the mean plus or minus SEM of at least 3 independent experiments.