Fig. 5.

Inverse relationship between 4E-BP1 and p53 protein levels in discodermolide-resistant cells. (A) Total 4E-BP1 (green) decreases, whereas total p53 (red) increases, with resistance to disco. (B) Immunofluorescence of p53 (red) and HDM2 (green) in A549 and AD32 cells. (C) Immunoblot of total p53, p21, HDM2, and 4E-BP1. (D) Immunoblot of p53 and phosphorylated p53 Ser15 expression in A549, AD32, and AD32^4E-BP1 treated with 50 μg/mL of cycloheximide (Chx) for the indicated times. Graph of the relative level of total p53 protein in indicated cell lines during Chx treatment. The p53 protein level at 0 h was normalized to GAPDH and set to a relative value of “1.” Values are representative of three independent experiments (±SEM).