Zou et al. (2011) reported that p27 and p57 control hematopoietic stem cells dormancy, while Besson et al. (2007) showed an association between p27 and bronchioalveolar stem cell expansion. Moreover, it is also known that p27 prevents the activation of RhoA (Besson et al., 2004; Wang and Lee, 2014) and that the inactivation of the RhoA-ROCK pathway enhances cancer stem cell propagation (Ohata et al., 2012; Tilson et al., 2015). This evidence concerns the gene CDKN1B and cancer.