Northern blot analysis for mRNA encoding eosinophil granule MBP in various leukemic cell lines. Lane 1, human basophilic leukemia cell line, KU812; lanes 2 through 5, human choriocarcinoma cells, BeWo (lane 2), Jeg-3 (lane 3), Nuc-1 (lane 4), and Jar (lane 5); lane 6, human eosinophil-committed leukemic cell line, YJ-11. The blot was sequentially probed with an MBP cDNA and an 18S rRNA cDNA probes to control for RNA loading.