Figure 4.

The caveolin-1^−ve CL1E-9 cells were transfected with plasmid harboring a full-length human caveolin-1 encoding cDNA under the control of a tetracycline-responsive element. A: A clone (C7) was selected and examined for its caveolin-1 expression, which was reduced nearly 15-fold on addition of 20 μg/ml of doxycycline (Dox) into the culture medium (left). Intense caveolin-1 expression was also confirmed in a constitutively expressing cell line, C6, but not in the mock-transfected CL1-0 cells (right). B: The invasive capability was correlated with the ability of cells to express caveolin-1. For C7 cells, addition of Dox to the culture medium resulted in a decrease in both caveolin-1 expression and invasion ability. Dox treatment or no treatment did not affect the invasion ability of CL1E-9 cells (B). C: Increased invasion ability was noted in C6 cells with constitutive caveolin-1 expression, as compared with that of the mock-transfected CL1-0 cells. D and E: The growth rates of caveolin-1^+ve C6 and C7 cells (with or without tetracycline treatment) compared with those of mock-transfected caveolin-1^−ve CL1-0 cells or CL1E-9 cells were similar, if not identical.