In serum free conditions, and after a finite number of mitoses, they cease to divide and differentiate. In order to maintain them in a proliferative state, we have transduced primary human MSCs with the retroviral vector encoding immortalizing gene v-myc. Stable immortalized cell lines of human MSC as described in the present study should provide unlimited number of homogenous cells derived from a single stem cell and facilitate follow up of progeny of the same stem cell for prolonged period, over many generations. When differences in behaviors are observed for different stem cells in different miniwells, one cannot discern whether these represent stochastic changes, or are the product of subtle differences in microenvironmental signals, or reflect a fundamental heterogeneity of the stem cell population. Immortalized stem cell line derived from a single cell can circumvent these problems and produces a clear-cut outcome. There is a concern about the use of oncogenes for generation of immortalized stem cell lines, as the oncogene in question might cause tumor/ectopic formation if cells proliferate indefinitely in the brain over time following transplantation. Although we did not find tumor formation in vivo in animals following brain transplantation of B10 human MSCs in the present study, we do not plan or project clinical trials in patients using the B10 human MSCs. There is, however, an alternative approach to circumvent this concern. We have recently generated immortalized human MSC lines by the conditional expression of v-myc under control of a regulatable tetracycline promoter. Addition of Tet to the medium activates the v-myc protein allowing the clonally isolated human MSCs to proliferate rapidly while holding differentiation essentially in abeyance; in the absence of Tet, the human MSCs cease proliferating and proceed to differentiate into various cell types. Previous works have demonstrated that human MSCs express genes characteristic of multilineage cell type prior to unilineage commitment. Rodent marrow derived-multipotent progenitor cells express Oct-4 as a necessary marker for pluripotency in stem cells and Otx1/2 expressed at early stages of neuroectoderm. Human MSCs also express Oct-4 and nestin as neural stem cell markers and even b-tubulin III, a neurons specific marker and GFAP, a marker for astrocytes, were expressed prior to undergoing differentiation. Moreover, proneural genes, Otx-1, Neurogenin 2 and Musashi 1 as well as Oct-4 and nestin have been expressed in mRNA level in human MSCs as reorted earlier in adult derived human MSCs. In the present study, B10 as a clonal cell line originated from a single human MSC, expresses Oct-4 and ABCG2 as general markers for stem cells, nestin as a neural stem cell marker, and Mash-1 and Otx-2. In general, ixabepilone, given as first line chemotherapy, has a manageable safety profile with neutropenia, sensory neuropathy, arthralgias/myalgias and fatigue being the most prominent adverse events incidence of severe neuropathy compared to the 3-weekly schedule. Likewise, in the present study, grade III sensory neuropathy occurred in 4/34 of the patients treated with the 3-weekly and in 8/30 with the weekly schedule. However, in all patients, except one, sensory neuropathy showed complete resolution to baseline or grade I after the completion of ixabepilone treatment.