HGF gene expression profiles in PCs of healthy individuals and patients suffering from myeloma. (A) Quantification of HGF mRNA in CD138+ cells isolated from bone marrow aspirates. HGF mRNA levels were profiled by the Affymetrix microarray 209961_s_at HGF probe set. Shown are signal strengths obtained by hybridization of mRNA to the microarray. Samples were from healthy individuals (NPC; n = 22); patients with monoclonal gammopathy of undetermined significance (MGUS; n = 14); smouldering multiple myeloma (SMM; n = 34); multiple myeloma (MM; n = 344), and human myeloma cell lines (HMCL; n = 45). (B) Statistical analysis of the microarray data from healthy individuals compared to patients with MM. HGF gene expression profiles in CD138+ cells isolated from bone marrow aspirates of healthy individuals (NPC; n = 22) and MM patients (MMPC; n = 344) were determined by microarray. The result of a two-tailed Mann–Whitney test is shown (p < 0.0001). (●) = mean, (▲) = maximum value, (▼) = minimum value, box = the distribution of the data set, and bars = standard deviation. (C) Linear regression analysis of HGF mRNA values measured in bone marrow core biopsies and in CD138+ cells isolated from myeloma patients. HGF mRNA in biopsies (n = 46) were quantified by real-time PCR and illustrated as relative quantities (R.Q.). From corresponding patients, CD138+ cells (n = 46) were isolated and HGF values were measured by microarray. Shown is the hybridization strength. Values were converted to log2 ratios prior to the linear regression fitting. (D) Linear regression analysis of HGF mRNA values in CD138+ cells aligned to HGF serum values of corresponding samples. HGF mRNA levels in CD138+ cells (n = 29) were determined by microarray. Strength of the hybridization signals are shown. In corresponding samples HGF serum concentrations were measured by ELISA. Quantified serum HGF is shown in pg/mL. Values were converted to log2 ratios prior to the linear regression fitting.