Cell viability following treatment with free PEG2K-VE, PEG2K-VE2, PEG5K-VE, or PEG5K-VE2 micelles in a mouse breast cancer cell line, 4T1.2, a drug-resistant cell line, NCI/ADR-RES, two human breast cancer cell lines, MCF-7, and MDA-MB-231, and an androgen-independent human prostate cancer cell line. PC-3. Cells were incubated with indicated concentrations of micelles for 72 h and cytotoxicity was determined by MTT assay. Values reported are the means ± SD for triplicate samples