Fig 2.

Interaction of tumor and microenvironment. Clone and microenvironment are the two factors that interact throughout the disease course. (A) When a clone is quiescent and microenvironment is nonpermissive (gold arrow) to myeloma growth, tumor burden (blue histogram) remains low and stable. (B) If a clone proliferates at a greater potential (white triangle), it can grow through the nonpermissive environment and elevate the tumor burden. (C) Conversely, microenvironment can be permissive to myeloma growth (red arrow) while proliferative potential remains stable. (D) When both factors are favorable to myeloma growth, tumor burden can increase rapidly.