After filtering out cells expressing <20% of genes and using only the cells consistently annotated as malignant in the six B-ALL samples, we found that a mean of 80.3% per patient of malignant cells express CD19 (“Methods”).  This result is consistent with the 0.8 baseline value of \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${lb}$$\end{document}lb we have used throughout the paper. The gene discussed is CD19; the disease is acute lymphoblastic leukemia.