Given the critical function of aldehyde dehydrogenase (ALDH) in promoting cancer stemness (Le Magnen et al, 2013), we also performed an ALDH assay and demonstrated reductions in ALDH activity in PlexinD1-knockdown C4-2BENZR and 22Rv1 cells but increased ALDH activity in PlexinD1-overexpressing LNCaP cells compared with respective controls (Fig. 6C). The gene discussed is LDHA; the disease is cancer.