ALDH1A1 and neoplasm: Interestingly, in tissues, CD44v3+ GC cells were localized at the invasion front of GC liver metastases, whereas ALDH1+ GC cells were more centrally located within the tumour mass as described by Liu et al.in breast cancer for the MET-like CSCs [29], but both expressed Ki67 proliferation marker (Fig. 3H).