RUNX1 and lymphoma: Indeed by 15 min, serum‐induced levels of C18‐S1P in the presence of ectopic Runx1 (pink bar) exceeded the sum of ectopic Runx1 (red bar) or FCS (gray bar) alone suggesting that ectopic Runx1 and FCS have additive effects in T lymphoma cells and that absolute levels of Runx1 modulate C18‐S1P production in vitro.