CA2 and neoplasm: Similar to the corresponding epithelial cells in vivo, the tumor tissue-derived organoid cells in the conditioned medium showed high expression of stem/progenitor cell marker OLFM4 and low expression of differentiation marker CA2, while normal tissue-derived organoid cells showed low expression of OLFM4 and high expression of CA2. However, tumor tissue-derived organoid cells and normal tissue-derived organoid cells cultured in a chemical-defined medium have similar expression patterns of CA2 and OLFM4, which cannot accurately mimic the expression patterns of the corresponding cells in vivo.