JAK2 and myeloproliferative neoplasm: To correlate JAK2 positive vs. negative in relation to IGF-1R levels in all MPN patients; although JAK2+ patients had more elevated values (160.6, 47.15–325.4) (n = 46) than did JAK2- patients (115.2, 66.61–280.6) (n = 25), no statistically significant correlation was found (results not shown).