Fig. 5. Freshly starved Ax-2 cells pre-incubated for 15 min in weak acid or weak base show an altered timing of rapid patterning. (A) 0-20 mmoll^-1 sodium propionate added to PB delays the patterning in a concentration-dependent manner at pH 6, but no effect was seen at pH 8. (B) The pattern becomes visible at t=1.5 min when cells are preincubated in 5 mmoll^-1 NH₄Cl at pH 8, whereas in the control it only becomes visible at t=3-5 min. The same effect is seen in 20 mmoll^-1 NH₄Cl at pH 8 but not at pH 6. (C) Similarly, the weak acid 5,5-dimethyl-2,4-oxazolidinedione (DMO) delays the patterning, and the weak base methylamine hastens it. Scale bar, 400 µm.