Northern blot analysis of poly-A⁺ RNA from various hematopoietic and nonhematopoietic cell lines and freshly isolated cells from buffy coat. (A) Five micrograms of poly-A⁺ RNA from the different cell lines (the B-lymphoblastoid cell line CESS, the erythroblastic-megakaryoblastic leukemia cell line HEL92.1.7, the promyeloblastic leukemia KG1a, the monocytic cell line U937, the erythroleukemia TF1, the T-cell line MOLT4, a fibroblast cell line [HFL], and the epidermoid carcinoma cell line [A431]) and from a primary culture of HUVEC was electrophoresed on a 2% agarose gel and subjected to blotting and hybridization as described in Materials and Methods. The hybridization with WASP probe (cDNA fragment from position 150 to 900) showed a major band of approximately 2.0 kb. Extended exposure did not show any WASP transcript in the endothelial cell line HUVEC, in the carcinoma A431, and in a fibroblast cell line (HFL). The blot was rehybridized with a β-actin probe for checking of uniformity loading. (B) Two micrograms of poly-A⁺ RNA from T cells (CD3⁺), B cells (CD19⁺), and monocytes (CD14⁺) was extracted and processed as described in (A).