The protrusions formed in response to TPA contain actin.

<p>On day 4, cultures of MCF10A acini were fed in A) the absence or B) the presence of 10 nM TPA (TPA). The cultures were fixed 15 hours after the addition of TPA and stained with phalloidin to detect actin (green) and DAPI to detect nuclei (blue). Images were captured by confocal microscopy (40X). Inserts show regions (in boxes) that were digitally enlarged to the same extent to compare protrusions (arrows in inserts) formed in A) control and B) TPA-treated cultures. C) On day 4, cultures of MCF10A acini were fed in the absence (control) or presence of 2 µM bisindolylmaleimide I (Bis). TPA or vehicle (control) was added 30 minutes later. The cultures were fixed 15 hours after the addition of TPA, and then stained to detect actin (green) and nuclei (blue) as described above. Bar = 50 µM. Representative images are shown.