Fig. 5. Inactivating ATP2C1 with siRNA blocks the Ca²⁺ response in DD keratinocytes. DD keratinocytes were cultured on glass coverslips until 40% confluent, then treated with ATP2C1 siRNA (see Materials and Methods). Forty-eight hours after treatment, at 50% confluence, cells were loaded with Fura-2 and intracellular Ca²⁺ was measured by the protocol detailed in Fig. 2. Ca²⁺ in the superfusing fluid was raised from 0.06 to 1.0 mM (black arrow). The Ca²⁺ response was blunted in DD keratinocytes treated with siRNA to ATP2C1 (top), whereas control DD keratinocytes responded normally to raised extracellular Ca²⁺ (bottom). The P value (Table 6) was calculated by a two-tailed t-test comparing vector control and siRNA. All values are expressed as mean ± s.d.