MST1 and cancer: The evolutionarily conserved Hippo protein is initially identified as a key regulator in various biological processes including cell proliferation, cell contact inhibition, and cancer development.5 Human ortholog of Hippo includes MST1 and MST2, and the corresponding signalling pathway generally functions in a tumour‐suppressing pattern by a kinase cascade.6 Briefly, MST1/2 phosphorylate and activate LATS1 (large tumour suppressor 1) and LATS2.