FIG. 4.

Western blot analysis of Id-1 protein expression in ECs cultured in conditioned medium. (A) ECs were grown in medium (None) as a control. ECs were cultured in conditioned medium (C.M.) collected from normal ECs. ECs were also cultured in virus-depleted, conditioned medium from KSHV-infected ECs (KSHV+, depleted C.M.) and in conditioned medium from KSHV-infected ECs (KSHV+, not depleted C.M.). ECs grown in conditioned medium collected from normal ECs had a 1.1-fold increase in Id-1 expression compared to that in control ECs. ECs cultured in virus-depleted, conditioned medium from KSHV-infected ECs had a 2.8-fold increase in Id-1 compared to that in control ECs, and ECs cultured in conditioned medium from KSHV-infected ECs had a 4.3-fold increase compared to that in control ECs. (B) Id-1 expression in ECs grown in medium (None) (as a control), KSHV-infected ECs (KSHV), ECs cultured in conditioned medium collected from normal ECs (C.M.), and ECs grown in conditioned medium from KSHV-infected ECs (KSHV C.M.). The fold increases in Id-1 expression compared to that in control ECs were 37.0 for KSHV-infected ECs, 1.7 for ECs cultured in conditioned medium collected from normal ECs, and 8.0 for ECs cultured in conditioned medium from KSHV-infected ECs. In each panel, the blot was probed for expression of Id-1 and reprobed for actin to demonstrate equal loading of the proteins. Representative experiments are shown. At least three independent experiments were performed and gave similar results.