De and up-regulation of MMP-9 by LTA. A recent study has indicated that induction of MMP-9 by IL-1b is mediated through Ca 2+ -dependent signaling [35]. Hence, we investigated the role of intracellular Ca 2+ in LTAinduced proMMP-9 expression, the intracellular Ca2+ chelator BAPTA/AM and ER Ca 2+ -ATPase blocker thapsigargin (TG) were used. As shown in Figures 3A and 3B, pretreatment with BAPTA/AM