cluster or group and evolving as a satellite) or internal processes (assumed to be tied to galaxy mass) is ongoing. To understand the relative influence of stellar mass and environment on galaxy evolution, it is necessary to isolate the processes responsible for the observed relation of star formation rate (SFR) to density. If the main cause is primarily internal processes, then it is the difference in the galaxy stellar mass distributions in different environments that leads to the SFR$-$density relation. In contrast, the environmental process alters the properties of galaxies of a given stellar mass. Therefore, by probing the SFR$-M_{*}$ relation, we can obtain insights into these two physical processes.

In our previous study, [@lin14], we confirmed that the group environment strongly affects the fraction of quiescent galaxies at fixed stellar mass, but no environmental dependence was found for the star-forming sequence, in good agreement with previous works [@bal04; @vul10; @koy13]. The result thus supports a fast environment-quenching scenario and favors galaxy mergers in groups to be the primary quenching mechanism. On the other hand, for the cluster sample, we found a global reduction of 17$\%$ in the specific star formation rate (SSFR) of the star-forming sequence compared to its 