Testing where in the cell Lyn is. This test may be a debug, if it doesn't localize, if may be because it doesn't need to associate with CD79A/B for very long to phosphorylate it, it may drift over to CD79A/B, phosphorylate it, then leave. A failure at this test may indicate the reason for a failure of Syk localization, but it does not indicate a problem with the BCR on its own.