Differences in apoptosis induced by facultative-pathogenic versus non-pathogenic mycobacteria in primary murine macrophages. Differentiated BALB/c BMDMs were infected at an MOI of 10:1 with M. smegmatis (Msme), M. fortuitum (Mfort), M. kansasii (Mkan), M. bovis BCG or left untreated (UT). The percentage of apoptotic cells was determined using a propidium iodide based staining protocol to detect the population of hypodiploid cells via flow cytometry at 20 h after infection. Representative histograms are shown in A. B. The average and standard deviation of three independent experiments is shown. For this and all subsequent figures asterisks indicate statistically significance with * = 0.05>p > 0.01, ** = 0.01>p > 0.001 and *** = p < 0.001 which was determined by using one way ANOVA using GraphPad Prism5.0 software.