Using global gene expression analysis, we found that a panel of commonly observed hypoxia-inducible genes [33–35], including BNIP3L, EGLN3, LOXL4 and P4HA1, were significantly upregulated in the EGFP+ MDA-MB-231 tumor cells, compared to the EGFP− cells (Fig. 1d). The gene discussed is P4HA1; the disease is neoplasm.