Background: Recent reports have demonstrated the ability of mesenchymal stem cells (MSCs) to induce differentiation of neuroblastoma (NB) cells. Properties of dedifferentiated fat cells (DFAT) are similar to those of MSCs. In this study, we investigated if DFAT can induce NB cell differentiation and suppress cell proliferation. Procedure: DFAT was obtained from mature adipocytes isolated from adipose tissue from a ceiling culture. NB cells were cultured in a medium with or without DFAT. Subsequently, these cells were cultured in a DFAT-conditioned medium (CM) with or without phosphatidylinositol 3 kinase (PI3K) inhibitor. The neurites lengths were measured, and the mRNA expression levels of the neurofilament (NF) and tubulin beta III (TUBβ3) were assessed using quantitative real-time RT-PCR. Cell viability was assessed by the WST-1 assay.