Phosphorylation of spleen tyrosine kinase at tyrosine 348 (pSyk³⁴⁸) may be a marker of advanced phase of Chronic Myeloid Leukemia (CML).

We investigated Syk as a potential marker of CML progression. We observed a significant over-expression of Syk mRNA and constitutive phosphorylation of Syk Y348 in blast cells from six AP or BP-CML, but not in 15 CML in chronic phase. We could follow in vivo the recurrence of pSyk(348) throughout blast cell escape, despite observing storage of dasatinib in blast cells.