To understand the mechanisms underlying the protective activity of MYSM1‐loss in B cell lymphoma, EuMyc tumours were harvested from Mysm1‐/‐ and control mice, and lymphoma cells isolated by cell‐sorting as live B220+ cells, for ex vivo analyses with qRT‐PCR and intracellular flow cytometry. The gene discussed is MYSM1; the disease is B-cell non-Hodgkin lymphoma.