MicroRNA expression profile and classifier for MCL. (A) Unsupervised hierarchical clustering of lymphoma samples, normal cells, and cell lines. MCL, SLL, DLBCL, and BL formed largely distinct clusters. A stromal cell–associated miRNA signature was more highly expressed in DLBCL and BL patients. There were also significant differences in the expression of miRNA associated with naive B cells, resting B cells, CB cells, and CC cells, with miRNA associated with naive and resting B cells being more highly represented in MCL and SLL patients. (B) An miRNA classifier derived using a Bayesian algorithm resulted in a 19-miRNA classifier (6 up-regulated and 13 down-regulated miRNAs) was able to separate most MCL patients from DLBCL and BL patients. The expression of this miRNA classifier is illustrated in SLL, normal cells, and cell lines. Orange boxes highlight naive B-cell and MCL cell lines.