Figure 5.

Multilineage in vivo differentation within tumors. (A) Spontaneous in vivo differentiation was monitored in immunodeficient mice following subcutaneous injection by comparing native and transduced MEFs. (B) Tumor growth was detected only from sites injected with transduced cells ater 1–2 weeks, followed by rapid expansion of tumor bulk, absent from native MEF injection sites. (C–F) Tissue was harvested at 4–6 weeks post injection. Cryosections and tissue staining demonstrated multiple lineages within the complex architecture of the nascent tumor and included muscle, keratin, glandular epithelium, and poorly differentiated tissues.