Lon is up-regulated in patient biopsy specimens and lymphoma cell lines compared with resting or activated normal peripheral blood B cells. Protein extracts (20 μg) obtained from cells as described in “Methods” and supplemental Methods, were immunoblotted with antibodies to Lon or actin. (A-B) Extracts from freshly isolated normal donor peripheral blood B cells that were positively selected using CD19⁺ magnetic beads (normal), as well as in normal B cells that had been cultured for 72 hours with activation of the TLR9 using CpG oligonucleotides, and the B-cell receptor using anti-IgM (activated), or untreated (resting). (A) Extracts from malignant DLCL cells from a patient splenectomy specimen (DLCL01) and DLCL cells from a malignant pleural effusion (DLCL-02), as well as in the diffuse large cell lymphoma (DLCL) cell lines OCI Ly-3, -7 and -19. (B) Extracts from Granta and Rec-1 MCL cell lines, MCL cells from a patient lymph node biopsy (MCL01) and in chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) cells from a patient lymph node biopsy (CLL/SLL01).