Figure 1.

Phg2 mutant cells present signs of abnormal development initiation. (A) Cultures of wild-type or phg2 mutant cells grown to their maximal density in HL5 medium (4 × 10⁶ cells/ml) were incubated for an additional 3 d. Phg2 mutants formed well-delimited cellular aggregates, whereas wild-type cells did not. Bar, 200 μm. (B) The formation of phg2 aggregates in these conditions coincided with an induction of contact site A (csA) expression as shown by immunodetection with an anti-csA antibody. (C) The expression of discoidin I (disc.) was assessed in cells grown at low cellular densities (below 10⁶ cells/ml). In these conditions, discoidin was overexpressed in phg2 mutant cells compared with wild-type cells.