Gene expression profile of MGF receptors. Expression of IGF-1R, IL-6R, gp130, c-met, TACI, and BCMA genes were determined with Affymetrix human U133 Plus 2.0 in 6 memory B cells (MBCs), 7 normal PPCs, 7 normal BMPCs, MMCs of 123 patients with previously untreated MM, and 20 HMCLs. □ indicates that the gene had an absent Affymetrix call in the sample; , the MBC samples; , the PPC samples; ▤, the BMPC samples; ■, the MMC samples; and , the HMCLs.