ALDH1A1 and mantle cell lymphoma: qRT-PCR analysis also showed significantly higher (>100-fold) expression of aldehyde dehydrogenase 1 (ALDH1) and ALDH2 in MCL-ICs than in MCL-non-ICs (Fig. 2b); this observation concurs with the high ALDH activity detected in MCL-ICs (Fig. 2e).