Exacerbated mTORC1 signaling in CXCR4^+/1013 mutant B cells. (A) Representative histograms for pS6 in splenic B cells nonstimulated (NS) or stimulated for 5 minutes with Cxcl12, LPS, or a combination of both. The impact of rapamycin on LPS+Cxcl12 stimulated cells is also shown. (B) Quantification of the frequency of pS6⁺ B cells among splenocytes nonstimulated or stimulated for 5 minutes or 24 hours with Cxcl12, LPS, or a combination of both in the presence or absence of AMD3100. (C) Frequency of splenic B cells in each cell cycle phase at day 2 after LPS stimulation in the presence or absence of rapamycin. (D) Frequency of PBs determined by FACS 3 days after LPS stimulation in presence or in absence of rapamycin. Results are from 1 representative experiment of 2 to 3 (A-C) or 2 pooled experiments (D) (mean ± SEM, n = 4 for A-C; n = 6-18 for D). Mann-Whitney U test was used to assess statistical significance (WT vs Cxcr4^+/1013: *P < .05, **P < .01; untreated vs AMD3100: ^#P < .05 [3B]; LPS alone vs LPS + rapamycin: ^#P < .05, ^##P < .01 [3C-D]).