A) Perp immunofluorescence demonstrating Perp loss in the epidermis of K14CreER;Perpfl/fl mice two weeks after tamoxifen injection. B) Genes differentially expressed between control K14CreER;wild-type and K14CreER;Perpfl/fl skin were identified using SAM (Significance Analysis of Microarrays) with an FDR of 10%. The 143 genes (51 induced and 92 repressed in Perp-deficient skin compared to control skin) are grouped by hierarchical clustering and represented in the heat map. C) Major classes of genes upregulated and downregulated in K14CreER;Perpfl/fl skin compared to controls, as determined by Gene Ontology (GO) annotation. Members of the metabolic process, transport, immune system process, developmental process, and cell communication categories were statistically significantly enriched (p = 6.73×10−4, p = 3.52×10−3, p = 8.91×10−3; p = 1.59×10−2, p = 2.47×10−2, respectively, by the binomial statistic). D) Table of genes induced 3 fold or greater in K14CreER;Perpfl/fl skin relative to control samples. E) Quantitative-RT-PCR analysis validating Il1f6 (* p = 3.1×10−5), s100a9 (* p = 0.00022), Chi3l1 (* p = 1.2×10−6), and Ccl20 (* p = 0.0002) as genes induced upon Perp loss. Graphs represent the average expression levels in the skin of five mice examined in triplicate +/− SEM. Statistical significance was calculated using the Student's unpaired t-test. F) Representative immunofluorescence images of CD3-positive T-cells in control versus K14CreER;Perpfl/fl mouse skin. T-cells are stained in green (arrows) and nuclei are stained with DAPI in blue. EP indicates epidermis and D indicates dermis, with white dashed line delineating the boundary between the two compartments. G) Quantification of CD3-positive T-cells in the skin of control and K14CreER;Perpfl/fl mice. Graph represents the average number of CD3-positive T-cells counted in triplicate 200× fields, from the skin of each of at least 5 mice, +/− SEM. Statistical significance was analyzed using the Student's unpaired t-test. (p = 0.21). H) Representative images of staining for toluidine blue-positive mast cells in control and K14CreER;Perpfl/fl mouse skin. Dashed box represents area seen in higher magnification (400∶1) images below. Note that mast cells are identified by the purple stain (arrows), which differs from the blue stained background due to pH differences within mast cells. I) Quantification of mast cell numbers in the skin of control and K14CreER;Perpfl/fl mice. Graph represents the average number of mast cells counted in triplicate 200× fields, from the skin of each of 5 mice, +/− SEM. (p = 0.7; Student's unpaired t-test).