Fig. (2) Caspase 3 activity in human fetal lung epithelial cells. Caspase-3 activity measured in cell lysates of immature and mature human fetal lung epithelial cells following cytokine exposure. Values are normalized for protein concentration and expressed as a percentage of 6 hour fetal control. Cytokine exposure resulted in an increase in caspase-3 activity in immature cells at all time point and in mature cells at 24 and 48 hours (*p<0.05). Cytokine-exposed immature cells had increased caspase-3 activity compared to cytokine-exposed mature cells at both 6 and 24 hours (#p<0.05).