Fig. S2. ATP-induced [Ca2+]i increases in MCC13 cells are mediated by P2X receptors.

Fig. S2. ATP-induced [Ca2+]i increases in MCC13 cells are mediated by P2X receptors. (a) Average trace of [Ca²⁺]ᵢ recordings in MCC13 cells showing the effects of ATP (100 μM) in the presence and absence of extracellular Ca²⁺. (b) Scatter plot summarizing the ATP-induced [Ca²⁺]ᵢ responses shown in (a). Responses are compared under normal extracellular Ca2+ conditions (1.8 mM; grey dots) and zero extracellular Ca2+ conditions (purple dots). Each dot represents data from an independent experiment (n = 8), with responses averaged from up to 14 cells per experiment. Data are presented as mean ± SEM. Significant difference is indicated (P < 0.001 vs. control; paired t-test). (c) Average trace of [Ca²⁺]ᵢ recordings in MCC13 cells showing the effects of ATP in the absence and presence of suramin plus PPADS. (d) Scatter plot summarizing the ATP-induced [Ca²⁺]ᵢ responses shown in (c), comparing responses in the absence (grey dots) and presence of suramin plus PPADS (orange dots). Each dot represents data from an independent experiment (n = 5), with responses averaged from up to 16 cells per experiment. Data are presented as mean ± SEM. Significant difference is indicated (P < 0.01 vs. control; paired t-test). [Ca²⁺]ᵢ was measured by live-cell ratiometric fluorescence imaging using Fura-2 AM and expressed as R/R₀.Supplementary figure associated with: Seo MS et al. Merkel cells release ATP in response to mechanical stimulation to mediate paracrine signalling. British Journal of Dermatology (2026). https://doi.org/10.1093/bjd/ljag067