Generally, at later timepoints, the CTC-enriched samples of patients who experienced tumor progression had higher mRNA expression of the CSC marker ALDH1A1, the anti-apoptotic gene BCL2, epithelial cell adhesion gene CDH1 (e-cadherin), the migratory adhesion gene FN1, and the immune checkpoint inhibitor CD274 (PD-L1) (Figure 3c). The gene discussed is ALDH1A1; the disease is neoplasm.