Trenbolone acetate, TBA, has been shown to increase proliferation and protein synthesis rates and decrease protein degradation rate in bovine satellite cell (BSC) cultures. Although we have previously shown that the androgen receptor is involved in these TBA effects, our current data show that 2 receptors from the erbB family, epidermal growth factor receptor (EGFR) and erbB2, also play a role in the effects of TBA on BSC proliferation, protein synthesis and protein degradation in BSC cultures. We have assessed the effects of treating BSC with AG1478, a specific EGFR tyrosine kinase inhibitor, and/or AG879, a specific erbB2 tyrosine kinase inhibitor, on the ability of TBA to affect proliferation rate (³H-Thymidine incorporation) in proliferating BSC cultures and to affect protein synthesis rate (³H-phenylalanine incorporation/mg protein) and percent protein degradation in fused BSC cultures. Statistics were done using Proc MIXED in SAS; the model included treatment as a fixed effect and experiment, BSC number and experiment replicate as random effects. Treatment with AG1478, AG879 or a combination of AG1478/AG879 significantly (P < 0.05) suppressed TBA-induced increases in proliferation. Treatment with AG1478 significantly (P < 0.05) suppressed specific TBA-induced increases in protein synthesis. Treatment with AG879 or a combination of AG879/1478 also decreased TBA-induced increases in protein synthesis (P < 0.05) although the effects of AG879 or AG879/1478 may be non-specific as there was also a significant (P < 0.05) decrease in protein synthesis rate in control cells (not treated with TBA) receiving these treatments. While treatment with either AG1478 or AG879 alone had no effect on the ability of TBA to reduce protein degradation rate in fused BSC cultures, treatment with a combination of AG879/1478 significantly (P < 0.05) suppressed TBA-induced decreases in protein degradation rates. In summary our results show that receptors from the Erb family are necessary to support TBA-induced effects on proliferation, protein synthesis and protein degradation in BSC cultures.