LRP6 phosphorylation contributes to BRAF-induced intestinal oncogenesis. (A) KRAS-mutated HCT116, BRAF-mutated HT-29, KRAS and BRAF wild-type Caco-2/15 and SW48 cells were treated with SCH772984 (1 µM) or DMSO for 1 and 6 h. Protein expression and phosphorylation were analyzed by Western blot. (B) Loss of LRP6 expression was determined by Western blot in IEC-6 cells expressing the inducible BRAFV600E:ER fusion protein, and shRNA against Lrp6 (shLrp6) or a control shRNA (shCtrl) and compared to non-transfected cells. (C) IEC6 BRAFV600E:ER cells stably expressing shLrp6, shCtrl or that were non-transfected were treated with 250 nM 4OH-tamoxifen 16 h before soft agar seeding. Cells were grown for 3 to 5 weeks in soft agar before MTT staining and colony counting. Three independent experiments are summarized in the graph. Data are expressed as mean ± SD. Paired t-test, ** p ≤ 0.01.