ALDH1A1, a marker of tumour stem cells in breast, prostate, colon, and lung cancers, is a cytoplasmic enzyme that is upregulated in tumour cells; ALDH1A1 is associated with poor prognosis of many tumours (breast cancer, melanoma, etc.)and has an important role in promoting tumour angiogenesis and metastasis and in acquiring resistance to anticancer drugs.146–148. Here, ALDH1A1 is linked to neoplasm.