Purpose: Breast cancer stem cells are responsible for tumor initiation, abnormal cellular proliferation and metastasis. The activation of breast cancer stem cells is regulated by many genes and the expression of tumor suppressors has a control over it. Speckle-type POZ protein (SPOP) is similar to tumor suppressor that their intact presence inhibits tumor development and any mutation in this gene is responsible for many cancer types. However the exact mechanism of SPOP in controlling cancer stem cells still has not been revealed. Materials and Methods: NOD SCID mouse was used for initiating breast tumor by injecting MDA-MB-231 cell type. The expression of ALDH1 and SPOP are analyzed using Immunohistochemistry and Western blotting. Results: The mice injected with tumor cells develop a primary tumor at four weeks and it develops advanced stage of breast cancer at nine weeks. Tumor formation and associated cellular complexity are observed through histological evidence. Also, the expression of ALDH1 shows overexpression pattern as tumor progress to the next level. Interestingly, the authors observed the expression of SPOP shows an abundant expression pattern in the initial stage of breast cancer and noticed its downregulated expression as tumor adverse. Conclusion: The results demonstrate that the highest expression of SPOP had a control over cancer stem cells in the initial stages of breast cancer.