FCGR1A and essential thrombocythemia: As illustrated in Fig. 5A, the coculture of MSCs isolated from a patient with essential thrombocythemia (ET) (MSC No. 38) and U937 cells increased the number of viable U937 cells treated with brequinar and significantly enhanced the expression of both CD11b and CD64 in AML cells treated with AICAr and brequinar.