Mouse anti 6x his tag antibody

A fluorescence ELISA-like cell-based assay was used to determine the cellular uptake of the peptide-fusion protein as we described previously [20 (link), 21 (link)]. Cancer and normal cells were plated onto a black 96-well plate with a transparent bottom and treated with 0 to 2.5 μM of the peptide-fusion protein or MAP30 for 24 h in quadruplicate. Peptide-treated cells were fixed with ice-cold methanol for 15 min at -20°C, washed with PBS and incubated with a coating buffer containing BSA for 1 h at room temperature. The cells were then incubated with mouse anti-6X His tag antibody (Abcam, UK) overnight at 4°C. After the washing steps, the cells were incubated for 30 min with an anti-mouse IgG labelled with a FITC fluorescent dye (Invitrogen, USA). The fluorescence signals were measured using Tecan Infinite M200 Pro fluorescence spectrophotometer (Tecan Group Ltd., Switzerland).