Breast cancer is originated from cancer stem cells (CSCs), which play critical roles in tumor metastasis and recurrence. However, novel therapeutic drugs for the eradication of CSC has not been established yet. Oncogenic signaling, such as Ras and Myc, has been reported to induce translation of specific transcripts that are involved in cancer growth and progression via translation factors. In the present study, we examined whether translation factors are involved in proliferation of CSCs. We isolated CSCs using a functional marker aldehyde dehydrogenase (ALDH) from luminal breast cancer cell line MCF-7. We analyzed expression of translation factors in ALDH-positive and negative cells by RNA-seq, and we obtained upregulated translation factors in ALDH-positive cells by two-fold or more. Translation factor X was also upregulated in triple-negative breast cancer cell line MDA-MB-231, compared MCF-7 cells. Next, we examined the effects of factor X on CSCs. Overexpression of factor X increased ALDH-positive cells in both MCF-7 cells and MDA-MB-231cells. In addition, overexpression of factor X increased tumorigenicity of MCF-7 cells in nude mice. These results suggest that factor X induces breast CSCs. We are now trying to explore the target protein which act at the downstream of factor X.