CRLF2 and leukemia: However, consistent with the apparent global up-regulation of Myc target genes in chronic Jak2 knockdown Eμ-Crlf2/Jak2R683G cells, c-Myc protein levels were prominently up-regulated in Eμ-Crlf2/Jak2R683G leukemia cells following sustained Jak2 depletion (shJak2.3323, C#8 M7 and M8) (Fig. 5G).