ALDH1A1 and ovarian cancer: Of note, it was reported that receptor tyrosine kinase-like orphan receptor (ROR1)-positive cells from ovarian cancer PDXs with a high expression of aldehyde dehydrogenase 1 (ALDH1) were more likely to engraft tumor into immune-deficient mice than ROR1-negative ovarian cancer cells, suggesting that ROR1 expression is associated with the engraft success 45.