MCL1 and adenoma: To ensure that the difference in ABT-199 sensitivity between early and late stage disease was not due to a difference between small intestine (SI) and colon-derived cultures, we also tested the sensitivity of Lgr5CreERApcfl/fl colon-derived organoids to BCL-2 and BCL-XL inhibition during transformation and observed strong dependency on both (Fig. 1e), while MCL1 inhibition again had no impact on adenoma outgrowth (Fig. 1f).