Fig. 1

Starvation induces the activities of Rab37 and autophagy together with increased TIMP1 secretion. a Lung cancer CL1-5 cells were treated with serum-free medium for 24 h. The level of TIMP1 protein in the conditional medium (CM), as well as the levels of active-form and total Rab37, LC3, and β-actin in cell lysate, were investigated using specific antibodies by immunoblotting. Active-form Rab37 (GTP-Rab37) was pulled down by GTP-binding beads in total cell lysate followed by Rab37 antibody detection. b Under starvation for 24 h, colocalization of Rab37 (red) and LC3 (green) labeled by secondary antibody conjugated rhodamine and FITC, respectively were investigated under multi-photon confocal microscopy. Scale bar = 10 μm. The quantification of colocalization of Rab37 and LC3 was conducted by randomly counting 30 cells. c The levels of secreted TIMP1 in CM of lung cancer H460 cells were evaluated under starvation conditions for 0, 24, 48, and 72 h by immunoblotting. Total proteins in the gel stained by Coomassie blue dye were used to represent equal loading. d Lung cancer cell H460 was treated with 0.5 μM niclosamide for 24 h under starvation conditions. The level of secreted TIMP1 (CM) as well as the levels of total Rab37, LC3, and β-actin in cell lysate, were measured by immunoblotting