(f) U937 cells were treated with the indicated siRNA and infected with virulent M. tuberculosis H37Rv. Autophagy was induced by starvation, or cells were kept in full medium, as indicated. Colony forming units were counted, and expressed as a percentage of the number of plated bacterial colonies from untreated cells, to assess bacterial survival. Data are means ± s.e.m. (n = 6; two independent transfections, 6 independent infections). Asterisk indicates P 0.05, and dagger indicates P > 0.05 (t-test) for the indicated data. 