To analyze the expression of genes important for B-cell development and lineage maintenance in EB tumor cells, we performed quantitative PCR analysis of cDNA from FACS-sorted wild-type and Bcl-xLTg BM late pre B cells (B220+IgM–BP-1–CD25+), healthy EB BM transplant recipients (B220+CD244+ BM; unaffected EB) and primary EB tumor isolates. Here, CD244 is linked to epidermolysis bullosa.