Tissue-specific deletion of Pten demonstrates altered proliferation and increased MC numbers in vivo. (A) PDMCs (1 × 10⁵ cells) from the indicated genotypes (age of mice, 16-24 weeks) were stained with toluidine blue. The controls, Pten^{wt/wtFcϵRIβCre+/wt}, and Pten^{wt/wtFcϵRIβCre+/+} mice were heterozygotes or homozygotes, respectively, for Cre expression at the FcϵRIβ locus and did not carry floxed Pten alleles. Cell surface expression of FcϵRI and Kit in PDMCs of indicated genotypes was determined. Cells (1 × 10⁵ cells) were incubated with PE-MAR-1 (anti-FcϵRI) and APC–anti-Kit. The mean fluorescence intensity was measured by flow cytometry. One representative of 3 individual experiments is shown. (B) PDMCs (5 × 10⁵ cells) were lysed in RIPA buffer. PTEN expression was determined by immunoblot with a monoclonal antibody to PTEN. β-actin was used as loading control. (C) Cell proliferation was measured by CFSE staining. Mean fluorescence intensity was measured by flow cytometry. (B-C) A minimum of 3 individual experiments were conducted. (D) Tissue samples were fixed with 4% formalin, paraffin-embedded, and sections stained with toluidine blue. MCs per millimeter squared was determined by direct counts of blinded samples. Statistical analysis was by an unpaired 2-tailed Student t test: *P < .05; **P < .01. Scale bar represents 100 μm.