3. A 30-year-old man presented for evaluation of abnormal nails. Physical examination revealed a red streak with distal V-shaped nicking. Numerous keratotic papules on the hands and chest and oral papules also were noted. The gene responsible for these findings encodes a Ca2+-ATPase responsible for a Ca2+ influx into what cellular structure?
a. cytoplasm
b. endoplasmic reticulum
c. golgi
d. nucleus
e. ribosome