This study identifies a key role for actin remodelling in the switch from the keratinocyte stem cell type known as a holoclone (cells with a high growth potential owing to the lack of differentiated cells) to a paraclone (keratinocyte stem cells with very restricted growth). Upon exposure to epidermal growth factor (EGF), holoclone colonies expanded rapidly through migration of peripheral cells and cell flattening, whereas paraclone colonies decreased in size owing to cell shrinking. In both cases, the effects were mediated through EGF-dependent changes in actomyosin contractility. Consistent with this, actin was organized radially in holoclones and circumferentially in paraclones, which also confirms previous observations. Notably, inhibition of RAC1, which regulates actin polymerization, switched the actin organization of holoclones to a pattern resembling that of paraclones, promoting a reduction in holoclone colony size and clonal conversion.