Fig. 1. Inactivation of Smad4 or Alk3 in Gli1⁺ stromal cells leads to intestinal mucosa tumefaction.

(A) Body weight changes of indicated mice compared with the starting body weight at day 30 post–tamoxifen administration (dpt). n = 6 mice for each group. (B) Survival rate of indicated mice after the last tamoxifen (TAM) administration. n = 8 mice for each group. (C) Representative images of large intestine at different time points after the last tamoxifen administration, and cyst-like polypus appeared at 60 dpt in GS4 mice (red arrow). Ctrl, control. (D) Representative images of hematoxylin and eosin (H&E)–stained large intestine sections and enlarged field of three large intestine segments at 30 dpt. Scale bars, 2.5 mm (left) and 500 μm (right). (E) Representative images of H&E-stained cyst-like polypus sections at 60 dpt. Scale bars, 200 μm. (F) Ki67 immunofluorescence staining in cyst-like polypus sections from GS4 mice at 60 dpt. The right panel shows the quantification of Ki67⁺ cells in the cyst-like polypus. Scale bars, 100 μm. DAPI, 4′,6-diamidino-2-phenylindole. (G) Crypt length quantification of three large intestine segments along with the time of conditional KO. PC, proximal colon; DC, distal colon; Re, rectum. (H) Representative images of Muc2-mCherry in vivo signals in distal colon sections at 30 dpt. The right panel shows the quantification of Muc2-mCherry⁺ cells along the crypt. Scale bars, 100 μm. *P < 0.05 and ***P < 0.001 by one-way analysis of variance (ANOVA) test in (A), (F), (G), and (H).