2.9. Cell proliferation assay
Crystal violet assay was carried out to measure the cell viability as described
previously (Wang et al., 2011). EC50 was determined as 50% viability relative to
the untreated control, as calculated using GraphPad Prism 5 software. 5-Fluorouracil
(5-FU) and dacarbazine (DTIC) were used as positive control for A431 and SKMEL-
28, respectively, because 5-FU is a commonly used drug for human squamous
carcinoma, and DTIC is the only drug for melanoma approved by both the United
States Food and Drug Administration and the European Agency for the Evaluation
of Medicinal Products (Tsao et al., 2004; Garbe and Eigentler, 2007). The morphological
changes of cells were observed under the microscope and recorded by the
Olympus 1X71 phase contrast inverted fluorescence microscope and analySIS image
capture software (magnification 100).
2.10. DNA cell cycle analysis
Cell cycle distribution of the untreated/treated cells was measured by flow
cytometry using