Effects of TPC2 agonists on cytosolic Ca ²⁺ in SH-SY5Y cells. (a and b) Ca²⁺ signals (mean ± SEM, n = 3–4 independent biological replicates) in cells expressing wild-type (a) and G2019S (b) LRRK2 in response to TPC2-A1-N (10 µM) in combination with increasing concentrations of TPC2-A1-P (10–60 µM). (c and d) Summary data (mean ± SEM from three to four independent biological replicates) quantifying the peak change in the Ca²⁺ signals in cells expressing wild-type (c) and G2019S (d) LRRK2. Each point represents the mean response from a cell population. **P < 0.01, **P < 0.01 (one-way ANOVA, Tukey’s test).