PTPROt overexpression decreases Ca²⁺ levels. Tet-inducible WT or mutant (DA and CS) PTPROt clones were cultured with or without Dox, serum starved, loaded with Indo-1 am, and analyzed for Ca²⁺ influx. Baseline values are represented on the left. At 30 seconds, cells were stimulated with goat anti–human IgG (▾). Subsequent Ca²⁺ flux is indicated on the right. The fluorescence ratio (530 nm/408 nm) is shown on the y-axis in relation to time on the x-axis. Note that a decrease in indo-1 am fluorescence correlates with an increase in Ca²⁺ levels. Each point represents the ratio for a single cell. The density of shading is proportional to cell number.