CCL21 up-regulates MMP-9 via ERK1/2 signaling. (A) B-CLL cells were treated or not with 1000 ng/mL CCL21 in the presence or absence of the indicated inhibitors (PT, 200 ng/mL; Wortmannin (Wmn), 30 nmol/L; the rest, 5 μmol/L). After 24 hours, the conditioned media was analyzed by gelatin zymography. (B) Western blots of lysates of B-CLL cells treated or not (10 minutes) with CCL21, and with or without the indicated inhibitors. (C) Reverse transcription-polymerase chain reaction analysis of c-fos in the same samples shown in (B). Vertical lines in (A) and (C) have been inserted to indicate a repositioned gel lane. (D) Flow cytometric analysis of CCR7 expression in untransfected (continuous lines), control siRNA- (dotted lines) or CCR7 siRNA-transfected (shaded areas) cells. (E) Gelatin zymographic analysis of the conditioned media of untransfected or siRNA-transfected cells treated or not with CXCL12 or CCL21 for 24 hours. Error bars represent SD. *P ≤ .05; **P ≤ .01.