To study whether the bone marrow cells primed by Id1-expressing tumour could stimulate ESCC cells to metastasize, KYSE150-luc cells were mixed with bone marrow cells from the three groups of ‘donor' mice, and then injected intravenously into the tail vein of ‘recipient' mice (Fig. 7c). The gene discussed is ID1; the disease is esophageal squamous cell carcinoma.