SUMOylation pathway activation and hyper-SUMOylation in Myc-induced murine B-cell lymphoma. (A) Myc alters the expression of critical SUMOylation genes. Expression profiling of genes encoding critical components of the SUMOylation pathway is shown. B220⁺ B cells from wt mice (ctrl, n = 4), premalignant Eµ-Myc mice (Eµ-Myc pre, n = 5), and Eµ-Myc lymphomas (n = 13) were used. For a complete list of analyzed genes, see supplemental Table 1. All probe sets shown exhibit a >twofold change. (B) qPCR analysis of total RNA isolated from wt B220⁺ B cells (wt, n = 3) and Eµ-Myc lymphomas (n = 3). (C) Immunoblotting of the indicated proteins comparing pooled wt (n = 7) B220⁺ B cells and individual Eµ-Myc lymphomas. (D) Immunoblot analysis using SUMO1 and SUMO2/3 antibody in pooled wt (n = 7) vs individual Eµ-Myc lymphomas. (E) SUMOylation pathway gene expression during B-cell development assessed by Affymetrix analysis (GSE15907, ImmGen). B cells from fetal liver (FL), bone marrow (BM), and splenic (SP) origin were analyzed. B.T1-3, transitional B cells; CLP, common lineage progenitor; LT-HSC, long-term hematopoietic stem cell; MLP, multilineage progenitor; ST-HSC, short-term hematopoietic stem cell.