Quantifying Cell Proliferation and Survival

Cell proliferation and survival were monitored by sulforhodamine B (SRB) and colony formation assays, as we previously described^{32 (link),53 (link)}. For validation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) colorimetric assay was simultaneously used along with SRB assay, as we previously described^{54 (link)}. IC10, IC25, IC50, and IC75 values were calculated via non-linear regression analysis using TableCurve 2D v5.01 software (Systat). For colony assay, 600 ~ 800 cells were seeded in 24- or 6-well plates and allowed to expand for 3 days in drug-free media. Drug treatment started at day 3 and lasted for 4 days and media was replaced and colonies were further incubated for additional 7 days in drug-free media. Colonies > 0.20 mm diameter were counted and quantified using the ColonyArea plugin in Fiji/ImageJ (NIH software). Cell confluence was determined using an automated cell counter (Luna-II, Logos Biosystems).