Figure 2: Progressive plasma cell neoplasms found in the Mef^−/−Rad50^s/s mice.

(a) The B220 and CD138 expression profile of bone marrow cells obtained from 6-month-old wild type control, Mef^−/−, Rad50^s/s, and Mef^−/−Rad50^s/s mice. The number shows the frequency of cells in each quadrant. (b) The frequency of CD138⁺ B220⁻ plasma cells in the peripheral blood is plotted vs the age of the mice. P value is 0.028, comparing the slopes of linear regression by ANCOVA: wild type vs Mef^−/−Rad50^s/s mice. (c) The hemoglobin concentration (g/dL) is plotted against the frequency of CD138⁺ B220⁻ plasma cells in the peripheral blood. P value is 0.015, comparing the slopes of linear regression by AVCOVA: wild type vs Mef^−/−Rad50^s/s mice. (d) Serum protein electrophoresis of 1-year-old wild type and Mef^−/−Rad50^s/s mice. The M-spike is indicated by the arrow. (e) The γ-globulin percentage of total serum protein is plotted vs the age of the corresponding mouse. P value is 0.037, comparing the slopes of linear regression by AVCOVA: wild type vs Mef^−/−Rad50^s/s mice. (f) Detection of osteolytic lesions by X-ray analysis of Mef^−/−Rad50^s/s mice (upper panels). The solitary osteolytic lesion is marked by the white arrow. The ratio of the bone density of the thoracic vertebrae and left femur, to the soft tissue density is calculated for the wild type and Mef^−/−Rad50^s/s mice (lower panels) (n = 6 each group). P values are 0.003 (thoracic vertebrae) and 0.007 (left femur), respectively.