LRP6 and lung cancer: In our experiments, knockdown of Kremen2 resulted in increased levels of p-LRP6 and LPR6 protein in H1703 cells (Fig. 4D) while the levels of p-LRP6 and LPR6 did not change obviously in A549 cells (Fig. S5), implying Kremen2 might play different roles in different lung cancer cells.