Figure 1. . MCF-12A cell embedded in Matrigel gradually form acini-like structures.

Optical microscopy images of MCF-12A. (A) Cells appeared in small clusters after 24 h. They gradually formed acini-like spheroids after 4 days (B), which grow in size after 10 days (C). Fourteen days after being embedded in Matrigel, spheroids preserved their size and some of them were more defined, with clear edges (D; arrowheads), while others were less defined (D; insert, arrows). Scalebars: 250 μm.