The replication of Study 32: [Chaffer et al., 2011][1] was [not pursued][2]; however, this project contains all information pertaining to the attempted replication of key experiments from this paper. It includes the detailed protocols, including reagents and author clarifications where they are available. <br> **Original citation:** Chaffer C.L., Brueckmann I., Scheel C., Kaestli A.J., Wiggins P.A., Rodrigues L.O., Brooks M., Reinhardt F., Suc Y., Polyak K., Arendt L.M., Kuperwasser C., Bierie B., Weinberg R.A. Normal and neoplastic nonstem cells can spontaneously convert to a stem-like state. Proc Natl Acad Sci U S A. 2011 May 10;108(19):7950-5. doi: 10.1073/pnas.1102454108. <br> **Original paper abstract:** Current models of stem cell biology assume that normal and neoplastic stem cells reside at the apices of hierarchies and differentiate into nonstem progeny in a unidirectionalmanner. Here we identify a subpopulation of basal-like human mammary epithelial cells that departs from that assumption, spontaneously dedifferentiating into stem-like cells. Moreover, oncogenic transformation enhances the spontaneous conversion, so that nonstem cancer cells give rise to cancer stem cell (CSC)-like cells in vitro and in vivo. We further show that the differentiation state of normal cells-of-origin is a strong determinant of posttransformation behavior. These findings demonstrate that normal and CSC-like cells can arise de novo from more differentiated cell types and that hierarchical models of mammary stem cell biology should encompass bidirectional interconversions between stem and nonstem compartments. The observed plasticity may allow derivation of patient-specific adult stem cells without genetic manipulation and holds important implications for therapeutic strategies to eradicate cancer. [1]: http://www.pnas.org/content/108/19/7950.abstract?sid=2d7d2f17-1950-4b89-83a2-2da2e5b0db54 [2]: https://osf.io/ucpye/