Fig. 6.

CBDA inhibits PKA activity. (A) (a) A representative photograph of phosphorylated bands and non-phosphorylated bands of PKA-specific substrate peptide in MDA-MB-231 cells incubated with vehicle (time 0, lane 3), vehicle (48 h, lane 4), and 25 μM CBDA (48 h, lane 5) was shown. For positive and negative controls, the reactions were performed in the presence (lane 1) or absence (lanes 2) of PKA catalytic subunit, respectively. An arrow in the image indicates wells that samples are applied. (b) The relative intensity of phosphorylated bands in MDA-MB-231 cells is shown. Data are expressed as fold change vs. non-CBDA-treated group (left panel; lanes 4 vs. 5), as mean ± S.D. (n = 3). *Significantly different (p < 0.05) from the vehicle-treated control. (B) MDA-MB-231 cells were treated with vehicle (indicated as Cont.) or 25 μM CBDA for 48, 72, or 96 h. After the treatments, cell viability was measured according to the methods described in Section 2. Data are expressed as the percent of vehicle-treated group, as mean ± S.D. (n = 6). *Significantly different (p < 0.05) from the vehicle-treated control. N.S., not significant. (C) A model of CBDA-mediated RhoA activation through PKA inhibition.