Figure 4.

The Src-inhibitory drug PD162531 stabilizes cell–cell contacts. (A) Phase-contrast time-lapse images of low-density HEKs (in low Ca²⁺), which were treated with 0.02% DMSO (control, upper panel) or 2 μM PD162531 (middle panel) or transferred to high-Ca²⁺ medium (lower panel). Treatment with PD162531 or high Ca²⁺ began at 0 h and was continuous for the duration of the experiment. Individual cells are indicated by arrows. Bars, 50 μm. (B) The mean time that individual keratinocytes grown under different conditions spent in contact with other cells in the culture was determined by observing time-lapse images frame by frame. The duration of each intercellular contact formed by every cell in the time-lapse field (typically ∼20 cells per experiment) was recorded and expressed as a percentage of the experiment time (6 h), and the mean contact time was plotted as percentage of time in contact. Thus, a value of 100% would indicate that all cell–cell contacts persisted for the duration of the experiment. (C) The migration of individual cells that did not come into contact with other cells (typically approximately six cells per experiment) was quantitated using Openlab software, and the mean pixels per frame value for control cells in low Ca²⁺ was defined as 100%. (D) c-Yes confocal immunofluorescence micrograph of HEKs maintained in low Ca²⁺. Specifically shown here is the contact region between two cells that have collided. Bars, 25 μm.