and a third one being the SIK2/3-class IIa HDAC pathway characterized herein and in another study (78) . Although only MEF2 is illustrated here, other transcription factors may also interact with class IIa HDACs and are subject to regulation by the LKB1-SIK2/3 axis. In addition, it remains to be investigated if this pathway regulates potential roles of class IIa HDACs in the cytoplasm. There is also evidence that LKB1 modulates cell polarity through SADs and MARKs (34,79,80) and controls cell senescence (81) and adhesion (82) via NUAK1.