Figure 3. Freezing and thawing has no impact on target occupancy.

FCCS measurements of XPO1 occupancy from HEK293 cells treated for 4 hours with 0, 0.01, 0.1, 1, or 10 μM selinexor from lysates processed immediately or after freeze-thaw. Cell lysates were coincubated with fluorescence labeled LMB (LMB₆₄₇) and ATTO488 labeled anti XPO1 antibody (XPO-1 AB₄₈₈) for 2 hours and measured on a ConfoCor2 Correlation Spectroscope. The absolute values for the XPO1 complexes were plotted. The resulting values were fitted to a logistic regression curve using the TIBCO Spotfire software package.