Figure 2.

Elevated expression of hPMR1 converts MCF-7 cells from non-invasive to invasive growth in extracellular matrix. MCF-7 cells carrying active and inactive hPMR1 transgenes were grown on cell culture inserts containing membranes coated with extracellular matrix. These were placed into 6-well dishes containing medium ± doxycycline and cultured for 30 hr, after which cells that migrated through the membrane were stained with Calcein-AM. An invasion index was determined by comparing the fluorescence intensity after trypsin/EDTA treatment of cells that migrated through coated membranes versus uncoated membranes. Shown is the mean ± standard deviation (n = 6). The double asterisk (∗∗) indicates P < 0.001 by Student's t-test. There was no statistically significant difference between treatment groups for cells expressing inactive hPMR1.