BCL2 amplification by Southern blot hybridization. In case nos. 6, 7, and 8 BCL2 amplification was detected, whereas tumors 9, 11, and 13 displayed no amplification. Case no. 9 is the t(14; 18) positive case as well as the case no. 11, in which the translocation occurred in the MBR region. Case no. 13 had a normal chromosome 18. Densitometric profiles show the amplification of BCL2 (b) in the first three cases, in which the signal intensity ratio varied from 1.7 to 2.1, whereas in the other cases it varied from 0.7 to 1.1. Probe 105-153A was used as a control, and the peak (a) corresponds to its intensity.