Loss of the Mmp3 gene reduces the in vitro tumorigenicity. Tumoroids were formed in the NanoCulture Plate (NCP)-based 3D culture with a serum-containing or stemness-enhancing medium. (A) Representative images of the LuM1 and MMP3-KO tumoroids. The upper panel shows the experimental design. (B–G) Tumoroid size quantification on (B) day 3, (C) day 4, (D) day 5, (E) day 6, (F) day 7, and (G) day 14 of the tumoroid growth periods. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns, not significant; n = 39 (LuM1 serum, MMP3-KO serum), n = 21 (LuM1 stem, MMP3-KO stem). The alternative graphs of Figure 3F,G with tumoroid plotting larger than 100,000 μm2 are shown in Figure S3. The experiments were repeated twice.