EGFR and arthritic joint disease: One study has reported that HB‐EGF levels are increased in osteoarthritis patient samples and HB‐EGF appears to inhibit the anabolic activity but stimulates the catabolic activity of articular chondrocytes.24 In contrast, another study showed that overexpression of a dominant negative EGFR led to arthritis in mice.25 Our current studies showed that HB‐EGF expression in Dermo1+ cells has severe adverse effects on articular cartilage during postnatal growth, especially on maturation and function of chondrocytes.