Effects of recombinant N-terminal proteins on rates of tension redevelopment (k_tr) relative to changes in force. (A) 5 μM C0C2 (triangles; n = 6) increased k_tr to near maximal at all levels of submaximal Ca²⁺ activation. (B) 5 μM C0C1m (triangles; n = 4) and 5 μM C1C2 (squares; n = 4) increased k_tr to near maximal at all levels of submaximal Ca²⁺ activation, whereas 5 μM C1m (diamonds; n = 6) increased k_tr to near maximal only at values at or below the pCa₅₀ for force generation.