HA increases ovarian cancer cell resistance to carboplatin. A. CBP dose response growth curves for ovarian cancer cell lines. LD50 for SKOV3, OV-90, OVCAR-3 and OVCAR-5 was calculated using exponential curve fitting. B. Cell survival of ovarian cancer cells treated with CBP (LD50 dose) ± HA (0–100 μg/ml) after 72 hr. HA treatment increased the survival of OVCAR-5 and OV-90 cells, but not of SKOV-3 and OVCAR-3 cells following treatment with CBP (LD50 dose). Data are expressed as percentage of no CBP control, mean ± SEM from 3–5 independent experiments performed in triplicate. *, significantly different from control (P < 0.05, independent t test).