Decreased proteasome activities of the 26S proteasome in A549 and H1299 tumor spheres.

<p><b>A.</b> caspase-like, <b>B.</b> chymotrypsin-like, and <b>C.</b> trypsin-like activity of monolayer culture and tumor spheres from A549 and H1299 cells was measued over the indicated times. <b>D.</b> End point analysis (120 min) of 26S proteasome activities in monolayer cultures and tumor spheres. Mean ± SD is plotted and derived from three independent experiments. Student's paired, and two-tailed t-tests were performed, *p<0.05, **p<0.01, and ***p<0.001 (three replicates per experiment).