FIG. 1.

Weakly and highly invasive breast cancer cell lines demonstrate weak and strong IL-6 gene expression, respectively. (A) MCF7, MDA-MB231, MDA-MB468, T47D, and ZR75 cells were left untreated (upper panel) or were treated with 2,500 IU/ml TNF (lower panel) for 5 h. Total RNA was isolated, and relative IL-6 mRNA transcription levels were determined by qPCR. (B) Total RNA was extracted from MCF7 and MDA-MB231 cells, left untreated or treated with 2,500 IU/ml TNF for various time points (as indicated on the figure). IL-6 mRNA levels from the two breast carcinoma cells were compared and normalized using housekeeping GAPDH mRNA levels by semiquantitative RT-PCR. Results are representative of two independent experiments.