ALDH1A1 and cancer: The immunohistochemistry results and Flow cytometry-based cell sorting (Fig. 1d, Supplementary Fig. S4e) showed positive expression of CD4419,20 and ALDH1A1 in peritoneal MCAs of exfoliated GC cells; The Western blotting results (Fig. 1e) also showed high levels of stemness-related genes, including CD44, ALDH1A1, Oct4, Bmi1 and Nanog21, in the peritoneal MCAs of exfoliated GC cells compared with scattered-free cancer cells.