Lei et al. (206) showed that LSD1 promotes β-catenin activation by inhibiting the expression of several suppressors of β-catenin signaling, especially prickle planar cell polarity protein 1 (PRICKLE1) and APC in LGR5+ liver cancer-initiating cells, by directly regulating the levels of mono- and di-methylation of histone H3 lysine-4 at the promoters of these genes. The gene discussed is PRICKLE1; the disease is liver cancer.