Serum stability and drug guiding capability of CD44-Apt1. (A) Biostability of CD44-Apt1. One nmol of phosphorothioate-modified CD44-Apt1 was incubated with human serum at a ratio of 1:9 for as long as 96 hours at 37 °C and then resolved in 3% agarose gel. (B) Growth inhibition effect on HCC cells by 5-FU with or without CD44-Apt1 conjugation. (Left) HKCI-C1 control (grey, circle) and CD44E/s cells (orange, square) were treated with concentration of 169pM to 10µM of the phosphorothioate-modified CD44-Apt1. (Middle) HKCI-C1 CD44E/s cells were treated with concentrations of 169 pM to 10 µM of CD44-Apt1-5FU (Red, solid triangle) or 14 µM to 30 mM of 5-FU alone (green, open triangle). (Right) Viability was measured using Celltiter-Glo, and growth inhibition percent was calculated. Half-maximal inhibitory concentration (IC50) was determined using the model of “log of inhibitor versus response with variable slope” under non-linear regression (mean ± SEM, N=4, each N with n=4).