Expression of BCL-2 in immunophenotypically distinct patient subsets according to treatment response. (A) BCL-2 expression in primary leukemic cells from eight B-lineage ALL and eight T-lineage ALL patients. In each subset, one half of the patients were rapid early responders (RER) and the other half slow early responders (SER). (B) BCL-2 expression in primary leukemic cells from 16 B-lineage ALL patients (eight RER and eight SER). (C) + (D) BCL-2 expression in 19 T-lineage ALL patients (11 RER, eight SER). In (A) through (D), NALM-6 cell lysates were used as internal standards.