In order to test whether these cytokines also promote the growth of MOPC315.BM cells, either 103 (low density) or 104 (high density) of these murine myeloma cells were cultured in 96-well plates, in medium containing either 1% or 5% FCS and with or without supplement of IL-6 and/or APRIL. Here, IL6 is linked to plasma cell myeloma.