Five core microcolony genes are essential for microcolony formation.

(A) Homozygous knockout mutants and wild type CAI4 cells were grown under static microcolony inducing conditions (RPMI with 5% CO2) for 20 h, and imaged using brightfield microscopy. Scale bar indicates 100 μm. (B) Microcolony density per square micron was evaluated for each strain using ImageJ. Data are means ± SD of n≥3 experiments, with * indicating significance by a post-hoc Tukey’s test at p < 0.05 as compared to WT.