This allows for the Domiphen Bromide determination of gene and protein features that may be seen during early stages of tumor cell migration into the surrounding stromal microenvironment. Finally, we utilized FT-IR spectroscopic imaging to determine hormone sensitivity in biological samples. This label-free and nondestructive technique was used to identify chemical signatures of disease states. We Raltegravir correlated gene expression and a loss of E2/ERa signaling with decreases in peak height in the C-H stretching region of the spectrum in 3D culture cell samples, consistent with prior observations that EMT is associated with changes in lipid profiles in epithelial cells. We also confirmed that MCF-7 cells become resistant to tamoxifen using spectral features, primarily in the peaks associated with nucleic acids. These results directly correlate optical profiles to cellular behaviors and genomics. Translating the cell culture results to patient samples, the in vitro chemical signature was also found in invasive breast cancer biopsies with differing levels of ER expression. These results indicate that FT-IR imaging can potentially be useful, alongside IHC and molecular marker analyses, to determine ERa functionality in patient tumor specimens. Though other imaging techniques such as positron emission tomography have been used for functional imaging studies before and after therapy, development of a similar approach at the microscopic scale is complicated by the need to also appreciate the cell type, morphology, and spatial phenotypic heterogeneity to understand the tumor and its microenvironment. FT-IR imaging can provide microscopic evidence rapidly and is applicable at the time of usual post-biopsy diagnoses in pathology. In conclusion, by combining molecular profiling with chemical imaging, we have demonstrated that mammary tissue fibroblasts can alter therapeutic response to anticancer agents and play a crucial role in controlling whether ER + breast cancer cells are able to respond well to hormone or become resistant to endocrine therapies.