Mechanical strain activates TACE. E17 (A, B, C) and E18 type II cells (D, E) isolated from wild-type (A, B, D, E) and TACE knock-out mice (C) were exposed to 2.5% continuous strain or 5% cyclic strain for the indicated periods of time. Activation of TACE was assessed using an active fluorescence FRET substrate as described in “Experimental Procedures.” Results are expressed as fold-change over unstrained samples. n = 4, *, p < 0.05; ** p < 0.01 versus control.