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. Author manuscript; available in PMC: 2021 Mar 25.
Published in final edited form as: Cell Syst. 2020 Mar 18;10(3):240–253.e6. doi: 10.1016/j.cels.2020.02.005

Figure 2. Primary keratinocytes exhibit an ‘idling motor’ ground state of pulsatile Erk dynamics.

Figure 2.

(A) Upper: representative single-cell traces of Erk activity in keratinocytes cultured in growth factor free (GF-free) media over 24 h. Lower: the mean number of pulses observed per cell for each hour over the 24 h timecourse. (B) Representative single-cell traces for MCF10A breast epithelial cells (left) and mouse keratinocytes (right) treated with increasing doses of epidermal growth factor (EGF). (C) The percentage of MCF10As (left) or mouse keratinocytes (right) that exhibited ≥ 2 Erk pulses over a 5 h timecourse after treatment with increasing doses of EGF. N=2 biological replicates (white circles); each replicate includes data from > 100 single cells. (D-E) Representative single-cell traces of Erk activity in keratinocytes shifted from GF-free media to complete media (in D) and from complete to GF-free media (in E) showing the reappearance of pulsatile Erk dynamics over time. (F) Schematic comparing the stimulus-dependence of pulsatile Erk dynamics in classical cell lines such as MCF10As (left) and primary keratinocytes (right). Instead of a flat landscape where dynamics are permanently altered by GF stimulation, keratinocytes adapt and return to a ‘ground state’ of pulsatile Erk dynamics.