Quantification of reporter activation by western blot. Lysates of cell line 16-1-3 (A) or 19-3-1 (B) were probed by western blots using an anti-DsRed antibody (left panels) or an anti-GFP antibody (right panels). Cell lysates were diluted as indicated. Note that the GFP antibody recognizes EYFP as well as ECFP. 1 μg/ml doxycycline or 1 μM Shld1 was added as indicated.