GAPDH and infection: Subsequently, infection with the variant strain AD169BADrUL131 (containing a functional UL131 that allows for pentamer expression and the ability to infect epithelial cells25) and TB40/E wt was analyzed by western blotting for CMV immediate early-1 (IE1) protein (Fig. 4b, lanes 1–14) and anti-GAPDH was used a loading control (Fig. 4b, lanes 15–28).