TAL1 and acute lymphoblastic leukemia: Strikingly, in T-ALL with aberrant activation of the oncogene TAL1, miR-223 is transcriptionally up-regulated by TAL1 itself and contributes to leukemogenesis through the translational repression of the tumour suppressor FBXW7 [49], once again indicating that the effect of a specific miRNA strongly depends on the cellular context.