CD4cre:PP4f/fmice develop spontaneous rectal prolapse and colitis with symptoms resembling Crohn’s disease. A, Visualization of rectal prolapse in the CD4cre:PP4f/f mice. Results from controls PP4f/f mice are also shown. B, Age of prolapse onset in the CD4cre:PP4f/f mice (n = 64). C, Mild splenomegaly and LN adenopathy in prolapsed CD4cre:PP4f/f mice. Results from controls PP4f/f mice are also shown. D-E, Haematoxylin and eosin staining of formaldehyde-fixed longitudinal (D) or transverse (E) section of normal PP4f/f (left column) or prolapsed CD4cre:PP4f/f colons (right column) are shown. Bars indicate 1000 μm (40X), 400 μm (100X) and 200 μm (200X) respectively. F-G, LPL (F) and IEL (G) cells were isolated and analyzed by flow cytometry for intracellular cytokines. Statistical analysis results on gated CD4+ (left panels) or CD8+ (right panels) cells are shown (n = 5-7). See Additional file1: Figure S1 for flow cytometry gating strategies.