ALDH-1 has been recently identified as a universal marker of cancer stem cells and progenitor cells thought to result in tumour regeneration as a result of the somewhat dormant presence of a small population of dysregulated stem cells following chemoradiotherapy with the capability to revive and generate tumours capable of recapitulating the heterogeneity of the parent tumour [31, 32]. The gene discussed is ALDH1A1; the disease is neoplasm.