ALDH1A1 and pancreatic ductal adenocarcinoma: Additionally, ALDH1A1 expression serves as a marker to identify a specific subpopulation of cancer stem cells in pancreatic ductal adenocarcinoma (Nimmakayala et al., 2021) Maryam Rezaee and colleagues reported that the expression of ALDH1, a CSC marker, is significantly elevated in tissues from patients with colorectal cancer (Rezaee et al., 2021).