Bronchosphere counts derived of ABC from IPF patients (n = 3) were obtained (A-D, 6a, 50 nM: p = 0.044, 20 nM: p = 0.044; 6d, 50 nM: p = 0.0161, 20 nM: p = 0.0161; 6h, 50 nM: p = 0.0229, 20 nM: p = 0.0229; 6l, 50 nM: p = 0.0047, 20 nM: p = 0.0307) and cell proliferation was tested by MTT assay (E-H, 6a, 50 nM: p = 0.023 20 nM: p = 0.044; 6d, 50 nM: p = 0.0113, 20 nM: p = 0.0228; 6h, 50 nM: p = 0.0163; 6l, 50 nM: p = 0.0053, 20 nM: p = 0.0441) in the presence of several HDAC6 inhibitors such as compound 6a (A, E), 6d (B, F), compound 6h (C, G) and compound 6l (D, H) in a concentration range of 1 to 50 nM. Bronchosphere counts and optical density values derived from the MTT assay correlated well. The data indicate mean ± SEM from triplicate measurements, n = 3. For statistical comparison repeated measures ANOVA followed by Friedman multiple comparisons test was used.