MKI67 and Hand-foot syndrome: To evaluate the hair‐promoting effect of AREG in vivo, multipoint subcutaneous injection of AREG (0.5 mg/kg body weight, every 48 hours) with or without one or both of the downstream pathway inhibitors [PI3K (wortmannin, 0.5 mg/kg body weight, every 48 hours) and MAPK (PD98059 [3 mg/kg body weight, every 48 hours]) to the shaved dorsal skin of 56‐day‐old C57BL/6 mice was performed, and skin pigmentation and hair growth were observed (Figure 6A), Ki‐67+ cells evaluated in HFs (Figure 6B, Figure S3).