In BCR/ABL1+ leukaemia, PAK1 and PAK2 are upstream regulators of the transcription factor STAT5 – a key node for initiation and maintenance of disease (Hoelbl et al, 2006, 2010; Friedbichler et al, 2010; Berger et al, 2014). The gene discussed is PAK1; the disease is leukemia.