R406 inhibits tonic BLNK tyrosine phosphorylation in DLBCL cell lines. DLBCL cell lines were treated with 4 μM of R406 (blue) or vehicle alone (green) at 37°C for 16 hours without crosslinking the BCR receptor (-BCR). Tonic BLNK phosphorylation in R406- or vehicle-treated cells was detected by single-cell phospho-flow cytometry. Gray lines represent cells stained with an isotype-matched control Ig.