Has both toxic and EGF activity. Its EGF activity consists of rounding cells (morphological change) and inducing tyrosine phosphorylation of the EGFR in A431 cells, but with a lower potency that human EGF. PD(50) is 215 ug/kg to crabs. LD(50) is >1000 ug/kg to crabs. Belongs to the EGF domain peptide family.