Lenalidomide treatment normalizes bone marrow mRNA expression and colony-forming potential. (A) Bone marrow expression of RPS14 as measured by quantitative real-time PCR is markedly increased with lenalidomide treatment and the concomitant reductions in 5q mosaic monosomy. Gene set enrichment analysis comparing pre- and post-lenalidomide-treatment bone marrow mRNA expression demonstrates significant increases in (B) erythroid differentiation program (False Discovery Rate < 0.05) and (C) a decrease in expression of p53 target genes, a putative mediator of ribosomal protein haploinsufficiency. (D) The in vitro colony-forming potential for BFU-E, CFU-E, and to a lesser extent, CFU-GM was also significantly improved with lenalidomide therapy. *P value of Student t test < .05; **P value of student t test < .005; ***P value of student t test < .001; error bars denote SEM.