Regulated volume decrease (RVD) following treatment with bone morphogenetic protein 6 (BMP-6) in vivo and in vitro. Salivary glands from AAV5-Bmp6–treated mice (n = 2) and AAV5-GFP–treated controls (n = 2) were collected, and cells were isolated. A, Relative cell volume was measured before and after hypotonic stress (HTS) stimulation in isolated primary salivary cells from AAV5-Bmp6–treated mice and AAV5-GFP–treated controls. B, The maximal percent RVD was determined, with a significant decrease observed in isolated primary salivary gland cells from mice treated with AAV5-Bmp6 compared with AAV5-GFP–treated controls. C, Relative cell volume was measured before and after hypotonic stress stimulation in HSG cells treated with recombinant BMP-6 in vitro or cultured with media alone (control). D, The maximal percent RVD was determined, with a significant decrease observed in HSG cells treated with recombinant BMP-6 in vitro compared with HSG cells cultured with media alone. Values in B and D are the mean ± SEM. P values were determined by Student’s unpaired t-test. See Figure 2 for other definitions.