It is expressed during the growth and synthesis phases of the cell cycle but not in the G0 phase (resting phase).7 The prognostic value of Ki67 has been investigated in a number of studies, and its potential as a reliable marker has been shown in cancers of the breast, lung, prostate, cervix, and the central nervous system.8 However, the role of Ki67 in the prognostic evaluation of GISTs is uncertain. This evidence concerns the gene MKI67 and cancer.