ALDH1A1 and neoplasm: Furthermore, the expression of colon cancer stemness markers CD133, CD44, and ALDH1A1 in mouse tumor tissues was detected by immunohistochemistry (IHC) and western blot, and the results showed that there were more CD133, CD44, and ALDH1A1-positive cells in the 5-FU + GRP78-exos group, and the level of their protein expression was markedly elevated (Fig. 3I–K).